Copyright by Munn & Co., 1881.

Scientific American Supplement, Vol. XXXII. No. 824 Scientific American, established 1845. ;

NEW YORK, OCTOBER 17, 1891.

{ Scientific American Supplement, $5 a year. ) Scientific American and Supplement, $7 a year.

RAIN MAKERS IN INDIA.

EVERY country subject to drought has its one 4 peculiar method of supplicating for rain, and that in| vogue in Kumaon in Northern India is not the least curious of them. Last winter the season was a very dry one in Kumaon, and consequently there was a/| failure of the crops, with great scarcity in the district. With the exception of a few showers, there were no winter rains, and that in a country where the popu- | lation is almost wholly dependent upon grain as a means of subsistence meant a famine and starvation. In consequence of the drought a Hindoo fakir imposed a penance upon himself, and was suspended by his feet from a wooden beam. In this position he was swung backward and forward for a _ considerable time by means of a rope attached to his body and

ulled by a fellowsaint. Both men were plentifally

daubed with cow-dung and ashes, and, save for a| small cloth round the waist, were minus all clothing. In such a case, should rain fall within reasonable time | after the penance, the fakir takes the entire credit for | the relief to himself, and rises immensely in the esti- | mation of the simple and credulous cultivator of the | soil. Our illustration is from the Graphic, London. | | a ncaa ee semi | RAIN MAKERS IN THE UNITED STATES. |

AT the instance of the Hon. Charies B. Farwell, Sena- |

tor from Illinois, an appropriation of $10,000 was made |

by the last Congress for experimental purposes relat- | ing to the artificial production of rain by firing explo- |

sives.

Senator Farwell has given an amusing account of how the appropriation was secured and his reasons for urg- | ing it. He makes no pretensions as ascientific wan ; he | never, like Espy and others, made a complete study of | the meteorologic laws and phenomena, but he learned | that in the high regions above the earth there were air | = currents charged with moisture, and became impressed | ; N ; h with the thought that by means of a sufficient number wn AL ay of first-class bangings the said woisture might be con- | w= densed and precipitated as rain. ‘* This idea,” he said, | “is old enough. I’ve been convinced of its practica- bility for twenty years, and probably other people |

UNITED STATES.

RAIN MAKERS IN THE

‘“*Even the Senate Committee on Appropriations laughed at me about this. When the Appropriation bill came over from the House, I went around to my colleagues of the Senate committee and said to them, ‘I want you to put $10,000 in there forrain.’ They laughed at me, but they put in the $10,000 just asa personal favor. When the bill went back to the House that $10,000 amendment was knocked out. I was one of the conference committee to whom the bill was re- ferred. I went to the other members and asked them to put in the rain appropriation just as an accommo- dation tome. The items in the Appropriation bill are | numbered, so when the conference committee reported | favorably on No. 17, nobody in the House cared to see | what No. 17, a little appropriation anyhow, was, and it passed.”

he accordance with this appropriation the Depart- ment of Agriculture has lately instituted the re- quired experiments, the same being under the imme- diate charge of Gen. R. G. Dyrenforth, assisted by Professor Car] Myers, the balloonist, Professor Powers, author of ‘‘ War and the Weather,” Mr. John T. Ellis, and George E. Casler, balloonist.

The place selected for the experiments was the cattle ranch of Mr. Nelson Morris, a few wiles distant from Midland, Texas, a quiet and far out of the way place, where the experimenting party were offered unlimited space and facilities for the undisturbed execution of their peculiar enterprise. Moreover, it is alleged this was a particularly dry spot, where little or no rain had fallen for three years. To this thirsty region came the rain makers, bringing with them a strange parapher- nalia, consisting of several dozen balloons, kites, re- torts, acids, iron filings, chlorate of potasb, sulphuric acid, manganese, rackarock, dynamite, fuses, pipes, electrical wires, dynamo machines, electric exploders, ete. It was August 5 when the party reached the ranch, and from that time onward they were very busy. After much toil their explosive supplies, gas apparatus, balloons, kites, and electrical devices were got into working order, and used as follows: By means of re- torts charged with chlorate of potash and manganese, oxygen gas was produced; hydrogen was generated by means of iron filings and sulphurie acid. With these gases forming a highly explosive mixture, the balloons

have. It’s just a question of applying what you know. ‘They know the required moisture is passing right over | were filled and time fuses applied.

Everybody knows there’s a certain amount of moist- | their heads all the time—going off, may be, to rain | The people see their corn | itself down some place where they're already drowned | and when it was ready, a dispute arose as to who

ure in the air all the time.

burn up and their cattle die for lack of moisture. | out.

It required four hours to charge the first balloon,

\should light the fuse. The chemist said the balloonist

wi i Wess

adil NO AR St

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SCIENTIFIC AMERICAN SUPPLEMENT, No: 824.

Ocroper 17, 1891.

should do it, and the latter said it was the duty of the chemist. Finally the chemist touched off the fuse and the balloon sailed away and exploded at about two milea from the point of ascension. A few sticks of rackarock were exploded on the ground, and that night rain fell at Midland and Stanton, twenty-five miles away.

This was regarded as a triumphant result. After that Gen. Dyrenforth gradually increased the number of explosives until during the last week of the experi- ments an almost continuous cannonading was main- tained.

The last of these rain-making experi Aug. 26 and is thus graphically described by the cor- respondent of the New York World:

* Aug. 26.—The night was beautifully clear, and not a cloud could be seen. The heavens were dotted with stars, and from all indications it was safe to predict that no rain would fail within forty-eight hours at the least. A strong gale was blowing toward the west. Five balloons were sent up and exploded, and 200 pounds of rackarock powder and 150 pounds of dyna- mite set off on the ground. There was, of course, no immediate result. The barometer was rising and the peedle was pointed at fair.

** By 3 o'clock in the morning a bank of clouds ap- peared on the western horizon at the int toward which the smoke and noise had blown. The sky rapidly became overcast, and by 4 o'clock there was rain, ac- companied by thunder and lightning. When the sun rose, it was seen that the storm had come directly out of the west, and on the horizon the clouds rose in a funnel shape, like the smoke from a volcano. There was a beautiful rainbow visible at sunrise. It ceased raining at about 8 o'clock.”

After hearing thie news, ‘“‘I think the experiments have now demonstrated the soundness of my theory,” said Senator Farwell to the World correspondent. ‘* For twenty years I have had no doubt rain could be produced in that way, and quite expected the experi- ments to be successful.”

‘* What are your plans respecting the practical ap- plication of the invention ?”

“Why, I think they could be stated in this way: The Secretary of Agriculture, you know, gets annual appropriations for the general purpose of advancing agriculture—that is, he gets money for eradicating diseases among cattle and for inspecting hogs, and for this and that similar thing. Well, when Prof. Dyren- forth makes his official report of these experiments, I that Mr. Rusk, the Secretary of Agriculture, will ask for $1,000,000, may be, or $500,000 any way, for rain making.

* The Department of Agriculture bas its inspectors and employes in the West, and when an inspector re- ports that rain will be needed at a certain time in a certain region, the secretary wil! send on his men and appliances and make the rain. That’s my idea of how it will be practically applied. Of course, I seek no control of any sort over the invention. If any State or other community wants to make rain on its own hook, there could be no objection to its doing so.” |

To us the most practical result likely to follow from these experiments is the extraction of money from the public treasury. We have seen how easy it was to ob- tain the first ten thousand dollars to aid the chimera. ‘*[ asked them to put in the rain appropriation just as an accommodation to me,” says the Senator, and they did it. ‘“* Nobody in the House cared to see what No. 17, a little appropriation anyhow, was, and it powee 4

The idea that rain can be precipitated by cannon firing is almost as old as gunpowder ; but while there are many curious coincidences, there is no satisfactor evidence that rain was so produced. It ison apar with the Chinese mode of conquering the enemy by making a loud noise.

It is true a downpour often follows a clap of thunder; but this does not prove the rain was uced by the concussiou. On the contrary, we Seow that rain probably results from the cooling of moisture-laden air, and simultaneously electricity may appear. Hence in thunder storms the aerial concussions are most probably the results, not the cause, of rain forma- tion.

Nature works on a vast scale in producing rain ; and it is idle to suppose that the burning of a little explo- sive matter can materially affect the boundless atmo- sphere of the skies.

In a certain sense it may be claimed that rain al- ways follows an explosion; since all atmospheric oe are successive. If to-day is fair, firea gun, and it will rain either to-morrow, or some following day. Uf to-day is rainy, fire = and it will be fair either to- morrow or afterward. There appears to be just as much sense in appropriating public money for explo- sives to produce dryness in Alaska as to make rain, by similar means, in Texas.

In conclusion, we would warn Senator Farwell and his coadjutor rain makers that they have infringed or a patented article, and are liable in damayes. The precipitation of rain by firing aerial explosives is the invention of Mr. Daniel Ruggles, of Fredericks- burg, Va., and was patented by him eleven years . to wit, on July 13, 1880, patent number 230,067. “His patent claim is as follows :

“The mode herein described of producing rainfall, said mode consisting in conveying and exploding tor- pedoes or other explosive agents within the cloud realm substantially as described.”

Mr. Ruggles’ invention was illustrated and described in the ScreNTIFIC AMERICAN of Nov. 27, 1880. We here reproduce the engraving and description then

ublished. “Novel Method of Precipitating Rain

alis. A has been recently issued to Daniel Ruygles, of Fredericksburg, Va., for a method of pre- cipitating rainstorms, which, judging from a well known precedent, is not entirely chimerical. It has been frequently noticed that heavy cannonading is followed by a fallof rain. Profiting by this suggestion Mr. Ruggles has invented a method of producing a concussion or a series of concussions in the upper re- gions of the atmosphere which he believes will induce the rain.”

The invention consists, in brief, of a balloon carrying torpedoes and cartridges charged with such explosives as nitroglycerine, dynamite, gun cotton, gunpowder, or fulminates, and connecting the balioon with an elec- trical apparatus for exploding the cartzidges,

ments took place

Our engraving represents an individual in the act of bringing down the rain.

r. Ruggles’ patent is still in force, and if the inven- tion has anything like the value which Senator Far- well places upon the obtained results, then the million dollars the senator ks of should go to the paten- tee. Let justice be done to inventive genius.

For the convenience of our readers and the further elucidation of the subject, we reprint the article we published a few months ago.

[From the Screntiric Amertcan of Dec. 20, 1890.) “THE ARTIFICIAL PRODUCTION OF RAIN.

“The question as to whether rain can be produced by artificial means is to be tested by the United States government. On motion of Senator C. B. Farwell, of Illinois, a clause was added to the appropriation bill which provides that, under direction of the Forestr Division of the Department of Agriculture, $2,000 shall be expended in experiments having for their object the artificial production of rainfall by the explosion of dynamite.

In a communication from Senator Farwell the fol- lowing theories are advanced: ‘‘ My theory in regard to producing rain by explosives is based partly upon the fact that after all the great battles fought during the century heavy rainfalls have occurred. This is historical and undisputed. Senator Stanford, one of the builders of the Central Pacific Railway, informed me lately that he was compelled to do a great deal of blasting through a part of the country where rain had never been known to fall in any useful quantities and where it has never rained since, and that during the period of the blasting, which was nearly a year, it rained every day. I feel almost convinced that rain can be produced in this way. The dynamite could be exploded on the ground or up in the air, and I thiak I would prefer the latter. The experiment should be made in eastern Iowa, Colorado, or in western Kansas, somewhere along the railway, and my own idea would be to commence early in the morning and explode continuously for seven or eight hours.”

The subject of rain production by means of concus- sion has been frequently discussed during the last twenty-five years. A great number of instances were stated by Francis Powers, C.E., in a volume entitled * War and the Weather, or the Artificial Production of Rain,” 1871. Many cases are cited in which great battles have been followed by speedy rain. Six oc- curred during our war with Mexico in 1846 and 1847; nine cases of battles or skirmishes are given which oc- curred in 1861 in the war of the rebellion, and which were followed by rain at no great interval; forty cases are cited in 1862, thirty for 1863, twenty-eight for 1864, and six for 1865. Eighteen similar cases are also cited from among the great battles which have occurred in Europe during the past century, waking a total of 137 cases. In a criticism of Mr. Powers’ theory, Silliman’s Journal said: **To this argument it may be replied that throughout the region from which his examples are mainly drawn rain falls upon an average once in three days, and probably a little more frequently ; so that from the conclusion of one rain to the commence- ment of another, the interval is on an average but lit- tle over two days. Now battles are not usually com- menced during a period of rain, generally not till some hours after the conclusion of arain. Rain, therefore, ought to be expected in about one day after the con- clusion of a battle. Now, the argument of Mr. Powers is lame in this point. He takes no precise account of the length of the interval between the conclusion of a battle and the commencement of rain, nor does he show that the interval is less than it should be if the battle had no influence in the production of the rain; and in particular he takes no account of the cases un- favorable to his theory, in which rain follows a battle only after a very long interval.”

Some of the cases, however, which may be cited where the fall of rain seems to have been caused by the discharge of cannon are very striking. During the siege of Valenciennes by the allied armies in June, 17983, the weather, which had been remarkably hot and dry, became violently rainy after the cannonading commenced. Two hundred pieces of heavy artillery were employed in the attack and one hundred in the defense of the city, the whole of which were frequently in action at the same time.

At the battle of Dresden, August 27, 1813, the wea- ther, which for some days had been serene and intense- ly hot, during the progress of the battle suddenly changed. Vast clouds filled the skies, and soon the surcharged moisture poured itself in a torrent of rain. At Waterloo, according to Siborne, the weather during the morning of June 17, 1815, had been oppressively hot. It was now a dead calm ; not a leaf was stirring, and the atmosphere was close to an intolerable degree, while a dark, heavy, dense cloud impended over the combatants. The 18th Hussars were fully prepared and awaited the command to charge, when brigade guns on the right commenced firing for the purpose of breaking the order of the enemy’s advance. The con- cussion seewed instantly to rebound through the still atmosphere and communicate like an electric spark with the heavily charged mass above. A violent thun- der clap burst forth, which was immediately followed by a rain which has never probably been exceeded even in the tropics. In a few moments the ground be- came perfectly saturated.

Humboldt says that when a volcano bursts out in South America during a dry season, it sometimes changes it intoarainy one. It is well known that in very hot calm weather the burning of woods, long grass, and other combustible materials produces rain.

ery extensive fires in Nova Scotia are so generally followed by heavy floods of rain that there is ground for believing that the enormous pillars of smoke have some share in producing them.

Captain James Allen, acting signal officer of the War Department, in reply to interrogatories recently addressed to him regarding the probability of produc- ing rain by artificial means, said: ‘‘One fact would seem to be easily admitted, that an attempt to explode gunpowder in order to practically demonstrate the ad- visability of attempts in rain production should at first be made after ‘most careful consideration of the atmo- —- conditions. For example, if these explosions should be made in the center of a high area, as shown by our weather maps, or even after a low area has

passed any point, we may be absolutely certain no rain will follow. The first experiments id be under. taken to the southeast or east of a low area, and 300 to 600 miles from the center.

“* Observing stations should be established every 5 or 10 miles for wiles to the eastward of the point of explosion. If the explosions are made in a compara- tively clear sky, and after that unmistakable clouds are observed to the eastward and not to the westward, some connection may be surmised. It must be said, however, that even if the production of rain be prac- ticable, it can only be for a very limited area, and it is believed that any benefit which can possibly arise from such rain can vever amount to the expense of the enterprise.”

The opinion of Captain Allen is similar to that of President H. C. Russell, of the Royal Society of New South Wales, contained in an anniversary address de- livered in 1884. Hesays: ‘*It would seem unreasona- ble to look for the economical production of rain under ordinary circumstances, and our only chance would be to take advantage of a time when the atmosphere is in the condition called unstable equilibrium, or when a cold current overlies a warm one. If under these conditions we could set the warm current moving up- ward, and once flowing into the cold one, a considera- ble of rain might fall, but this favorable condition seldom exists in nature.”

The experiment of producing rain by exploding dy- namite is about to tried, and the result will be awaited with much interest.”

The foregoing was published in the ScIENTIFIC AMERICAN of September 5th.

After the rain makers had telegraphed from Texas to all parts of the country announcing the wonderful success of their bombs, it was discovered that the me- teorological records for that locality had indicated 'pro- babilities for rain for a day or two in advance of the firing, and that the rain would have fallen all the same without any burning of powder or sending up of bal- loons. There seems to be little room for doubt that the swinging of a Hindoo head downward, as illustra- ted in our engraving, is just as effective for producing rain as the making of loud noises.

The strongest theory and argument of the American rain makers, to wit, that rain is often occasioned by claps of thunder, will not bear the test of scientific re- search. Electrical action may take place when rain is formed and the thunder may be therefore a result of rain formation, not thecause. A correspondent in Nature takes the same view. Among other comments upon the Texas experiments, he says :

‘It isneedless tosay that popular theorizing, on this ason most other physical phenomena, concerns itself chiefly with the things that are most obvious to the senses, but often have little or nothing to do with the process. Thus we find that attention has been fixed on the explosion ; and we are told that the idea of breaking clouds by producing a motion in the air, and so destroying the equilibrium of the suspended globules of moisture, which in coalescence form rain, isnot a new one; that it was the custom to keep a eannon in French villages, with which to fire at pass- ing clouds and thus hasten the downpour ; that at the battles of Dresden and Waterloo the concussion of the air by the cannonade led to the descent of torrential showers ; and we are reminded that ‘in the same way’ rain follows a peal of thunder caused by the pass- age of a lightning flash through a moisture-laden at- mosphere, etc. Now all this noise and disturbance have no more to do with the production of rainfall than has the thrashing which the village rain-maker of Central India receives from his fellow villagers to stimulate him to fresh exertions when he is thought to have ne- glected the performance of his official duties, or the London street-boy’s whistle, with which Sir Samuel Baker startled a rain-making king in the Southern Soudan, and which was followed by such a deluge that even the rain-making potentste implored him to arrest the working of the spell.* The effect of a concussion, as such, is to produce an instantaneous compression of the air, and a momentary heating in a wave which travels away at the rate of about 1,000 feet per second, and is incapable of generating any translational move- ment of the atmosphere, and certainly of promoting condensation. Nor do we know of any recorded ob- servations in support of the idea that it can cause the coalescence of cloud corpuscles into raindrops. Neither does the concussion of the air by a thunder clap stand to the downpour that follows it in the phys- ical relation of cause to effect. In this case Sir John Herschel adopts the opinion originally put forward by Eeles, that the order of succession is the reverse of that here assumed, that the formation of the rain-drop is the antecedent phenomenon, and the lightning flash (and ergo the thunder) the consequent ; the elec- trical discharge being determined by the sudden con- centration of the electricity of (say) one thousand cor- puscles on the surface of the single resulting rain-drop, in which case its intensity would be increased ten-fold. What causes the coalescence is still a matter of much obscurity, though sowe light has been thrown upon it by the ingenious experiment exhibited by Mr. Shelford Bidwell at the Royal y~e conversazione on May 14, 1890, and described in vo). xlii. (p. 91) of this jour- nal. When the shadow of a small (condensing) steam jet was thrown upon a white screen, under ordinary conditions, it was of feeble intensity and of a neutral tint ; but when the jet was electrified, the density of the shadow was at once greatly increased, and it as- sumed a peculiar orange-brown tint. It appeared that electrification promoted the coalescence of the exceed- ingly minute rticles of water contained in the jet, thus forming drops large enough to obstruct the more refrangible rays of light. On this view, then, electri- fication would appear to be the cause of coalescence, and the electrical discharge the ulterior result ; but a8 yet we know too little of the molecular processes con- cerned in the formation of #rain-drop to attempt any- thing like a complete theory.

“In conclusion, while we cannot but recognize the high interest of General Dyrenforth’s results, with the imperfect information at present before us we cannot regard them as conclusive. It is the characteristic weakness of all experiments of the kind that many of

* This story has probably been told by Sir Samuel in one of his well- known works on Africa, and is too good to be spoilt by condensation. It is, at all events, authentic, the present writer having heard it from his own lips at a Simla dinner-table,

Ocroser 17, 1891.

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the essential circumstances are scarcely ever recorded, or perhaps even capable of being brought within the limits of observation ; and thus the logical conditions of a proved conclusion cannot be fulfilled. For in- stance, it is very unlikely that is known of the state of the atmosphere in respect of its humidity and its vertica) temperatare decrement at the eleva- tion at which the balloons were exploded, and yet, as we have seen, these data lie at the very root of the whole matter. However, arrangements are being wade for farther operations at El Paso and in western Kan- sas, so that it will not be long before the highly inter- esting and practically important problem of st mulat- ing the precipitation of.rain will receive a more satis- factory solution. H. F. B.

ARTIFICIAL RAIN MAKING.* By Prof. Epwi1n J. Houston.

WHENEVER a large mass of air is cooled below the temperature of its dew point, the moisture it can no longer hold as invisible vapor becomes visible. If the reduction of temperature be but slight, the ap- pears as fog, mist, or cloud ; if the reduction con- siderable, as rain or snow.

There has been no little attention given lately to the question as to whether or not rain can be caused to fall at pleasure on any given section of the earth—rain machines, or artificial rain producers, consisting essen- tially of devices whereby explosions of nitro-glycerine, or other similar substances, are obtained at fairly con- siderable elevations in mid-air, have been tried in dif- ferent forms. As tothe success of these attempts at the artificial production of rain, the testimony appears to be uncertain or contradictory.

The idea of rain making by mid-air explosions is probably based on the rains that are generally believed to attend or follow great battles, 4th of July cele- brations of the Chinese character, and volcanic erup- tions. Passing by the evidences produced by either the warlike or the peaceful burning of gunpowder, which at best are but vague, it may be remarked that voleanic eruptions nay produce very heavy rainfalls, not only because the force of the eruption and the in- tense heat cause upward currents in the air, but also because of the vast quantities of vapor of water that escape from most volcanoes during their eruptions.

There isa fascination in witnessing man’s struggle with the forcesof nature ; a struggle, be it understood, not made to oppose such forces, but rather to direct them. The former effort would be foolish, the latter must meet with success if properly directed.

Do the scientific facts, as far as known to meteor- ology, give any encouragement for the continuance of the efforts of the would-be rain makers? Let us in- quire:

It is now generally agreed that the lowering of tem- perature necessary for the production of rain may be obtained in the following ways :

(1.) By the intermingling of masses of warm and cold air.

L. By the carrying of warm, moist air into a cold place.

In any case the cause of the rain is, briefly, the cool- ing of the air until it is unable to retain all the moist- ure it formerly held as invisible vapor, and deposits the excess in a visible form as rain.

The quantity of the rainfall will, therefore, depend both on the amount of moisture present in the air and on the extent of reduction of temperature produced.

The first method, viz., the lowering of temperature by the intermingling of masses of warm and cold air, can never produce any very considerable rainfall, since, though the warm air is cooled by its mixture with cold air, and the tendency is, therefore, to cause the mixed air to become relatively moister, yet at the same time the cold air is made warmer, and, therefore, relatively drier. Drizzling rains might be produced in this man- ner, but scarcely ever heavy rainfalls, unless both the cold and the warm air contain large quantities of moisture.

There remains, therefore,{but the second way of low- ering the temperature of the air, viz., by the carrying of the warm air into a colder place. This can be ac- complished in three different ways :

(1.) By a change of latitude, or by a warm, moist air blowing into a colder latitude. In general, the equa- torial currents blowing toward the poles are the chief rain producers.

(2.) By a change in altitude, effected by an ascending current, due toa heated area. Here the lowering of the temperature is due not only to the cold of eleva- tion, but also to that produced by the expansion of the air under lower pressure.

(3.) By a change in altitude, due toa mountain range opposing the progress of a wind, and thereby necessi- wie its gradually creeping up the sides of the moun-

In any of these ways heavy rains may be produced, and, in point of fact, they are probably the only ways in which heavy rains are generally produced.

Applying the preceding principles to the case of the modern rain machine, let us inquire as to the proba- bilities of its successful operation. The simultaneous or the successive explosion of large quantities of any high explosive in the upper regions of the atmosphere must produce, in general, a rapid and more or less thorough mixing or stirring of the surrounding air.

_ The sudden expansion of the air both by the heat liberated by the explosion and by the gases evolved qusien the explosion is attended ‘by a rush outward, ollowed by a rush of air inward, toward the explosion center. The direction of this latter rush is generally aenly inward. In addition to these inward motions,

e heat generated may tend to produce a slight up- ward motion ; the general effect must be, however, to = & mixing or churning rather than an upward in The immediate effect of the explosion is to produce oi niature area of low barometer, caused by the ra- se of air toward the explosion center, and by li atever ascending current that may result from the

of heat.

, +t would be reasonable to suppose that if the explo- oo Produces any direct effect in atmospheric pon ~9 “tons, the area of low barometer should follow imme-

r aaa we before

the electrical section of the Franklin Institute, Sept. 8,

diately, or nearly so, after the explosion. Have such changes in the barometric pressure noticed to follow such mid-air explosion ?

So far as the mixing motion is concerned, its action to produce a fall of rain must be slight. The ascend- ing motion might cause a rainfail, but as this motion is slight in extent, its action under ordinary conditions must at best be but insignificant.

In either case; any decrease in temperature, and con-

uent increase in relative humidity, must necessarily be slightly decreased by the dry and heated gases evolved during the explosion of such substances as nitro-glycerine, dynamite, or gunpowder.

It might be supposed from the above considerations that. balloons containing an explosive mixture of hydrogen and oxygen would be preferable to those carrying nitro-glycerine dynamite or gunpowder, since in the former case the vapor of water results from the explosion, and in the latter dry gases. It must be remembered, however, that the explosion of mixed oxygen and hydrogen produces for the greater part a collapse or radial rush inward toward the explosion center, while the explosion of gunpowder or nitro-

lycerine produces for the greater parta radial rush

rom such center.

A circumstance that appears to have been lost sight of in allthe recent attempts at rain making is that such attempts have been apparently wade irregardless of the hygrumetrie conditions of the air. As rain is but the excess of moisture, the warm moist air is unable, when sufficiently cooled, to retain the amount of the fall, which will depend, as stated, on the quantity of moisture in the air as well as on the extent of the chilling action following the explosion or other cause. To attempt to produce rain by explosions in mid-air, irrespective of the quantity of moisture in the air, is to attempt to cause water to fall from the air when prac- tically none is present. This is not only illogical, but absurd.

It may be thought by some that the concussions eaused by mid-air explosions might result in such a general movement of the surrounding air as to cause rain to fall over an extended area. The flash of the explosion is followed by a sudden movement of the air, causing the noise of the explosion. The phenomena of lightning and thunder are somewhat similar to those of artificial mid-air explosions. First we have the lightning flash, and subsequently the thunder, which is a violent concussion of air. Does this concussion bring down a heavier rainfall? Popularly it is believed to do so, but the general opinion of the scientific world is that the lightning flash is the effect of a rapid con- densation of the aqueous vapor, 7. ¢., of a heavier rain- fall, and not the cause of such a fall. That is to say, the high potency of the lightning flash is due to the enormous decrease in the surfaces of the already charged rain drops over that of the surfaces of the thousands of the separate drops that coalesce to form the single drops.

Nevertheless, the liberation of heat energy and the rapid admixture of air following the disruptive dis- charge may slightly increase the rainfall, or may act as a determining cause of rain over an extended area.

There is this difference between the lightning flash and the flash of an explosion, viz.: The former occurs over a comparatively great length of path, 7.e., a space of small breadth and depth but great length.

The latter occurs in a comparatively limited space, the three dimensions of which are nearly equal.

Though lightning is not a cause of rain, there can be no doubt that if rain can be artificially produced dur- ing a period in which there is much free electricity in the air, the storm will be attended by lightning and thunder. If then there be any increase of rain due to the presence of lightning, artificial rain making will be more liable to succeed when the potential of the air, as regards the earth or neighboring clouds, is comparatively high.

The enormous expenditure of energy required to produce a rain storm over an extended area is a circum- stance that would appear to give but little encourage- ment to man’s many efforts in this direction. The amount of energy liberated by the greatest explosion man has yet effected in mid-air is but insignificant when compared to the energy liberated by nature dur- ing even a comparatively limited fall of rain.

There is, however, an important consideration bear- ing on the question of the probable success of rain making by mid-air explosions that gives to such attempts a far greater probability of success than would appear to be warranted from the facts already enumerated. Presupposing the existence of a sufficient mass of moist air, at preferably a comparatively high difference of potential as compared with the neighbor- ing air or the earth, a mid-air explosion might act as the determining cause of rainfall over a wide area. The balance of the energy requisite therefor being supplied by the moist air. In a mass of very moist air there exists a store of energy which, if liberated, would suffice to cause movements of the air of vast extent. When the vapor of the air is condensed, the potential energy becomes kinetic, and, being liberated by the heat, causes ascending currents, which produce a further condensation of moisture, and further libera- tion of energy previously locked up in the vapor.

There sometimes exist conditions in the air in which it is, so to speak, ina state of very unstable equilib- rium, and a slight determining cause may result in the liberation of the stored-up energy with a resulting heavy rainfall. In such cases it would appear that there are no reasons why an explosion in mid-air should not be followed by rain. At the same time it is not unreasonable to suppose that the natural causes would, in many cases, coutinue to act and thus cause rain without artificial aid.

There are, however, meteorological conditions that seen frequently exist in certain latitudes in which

eavy rains might be artificially produced by mid-air disturbances when without such disturbances no rain- fall would occur. Should, for example, a layer of warm, moist air exist between the earth’s surface and a higher layer of cold, moist air, separated by a com- pase thin layer of air, and such conditions ex-

t as to maintain the two layers separate, then the breaking or piercing of the intermediate separating layer might permit such an up-rush of the warmer air through the opening that the liberation of its stored- up energy through the condensation of its moisture would result ina general up-rush of the warm moist

air and the consequent production of an extended area of jow barometer. In other words, the artificial rapture of the separating layer would result in the formation of a true storm center and a heavy rainfall of consider- able dimensions. In such cases it would appear :

1. That mid-air explosions will be more effective than explosions on the earth’s surface.

2. That direct mid-air explosions 7%. e., explosions in which the general effect of the liberated enercy is to produce an upward rush of air, would be more ef- fective than undirected, haphazard explosions.

If in such cases considerable difference of potential exist between the layers of air, or between that of the air generally and the earth, the lightning flashes would unquestionably be effective in piercing the separating layer, especially if, as would probably be the case, the

meral direction of the discharge be between the ayers of cold and warm air.

Since, as we bave seen, it is the ascending current that causes the heaviest rainfall, it would appear that mid-air explosicns of such a character as to produce in general an upward rush of air would be probably more successful than undirected, haphazard explosions in rmoid-air. Such movements might advantageously be effected by the liberation of rockets with enlarged conical heads, or any form of fire work that would move generally upward.

Since success in artificial rain making is probably de-

ndent on the meteorological conditions, both of the Leer and upper layers of the atmosphere, efforts should be made to enlarge our present very limited knowledge of such conditions.

Captive balloons, containing registering electrome- ters, tele-thermometers, tele-hygrometers, tele-anemo- meters, ete., might be connected by wires with record- ing apparatus placed on the earth’s surface. The cost of maintaining ‘such aerial stations of observation would be but insignificant when compared with the benefit that would accrue not toward the solution of the

roblem as to the probable success in rain making, Pat the general operations of the United States Weather Bureau in particular, or of meteorology in general.

During the general prevalence of moist warm air, when but a slight cooling is necessary to cause a general downpour, effective rain making might be ob- tained by the sudden breaking or opening of cylinders of liquefied gases, whose expansion would cause an in- tense chilling of the surrounding air; such cylinders could be readily opened by means of earth-controlled electromagnets.

The following general conclusions may, in view of the present state of metallurgical science, be properly drawn concerning the artificial production of rain :

(1.) That rain can never be made to fall at will by mid-air explosions on any part of the earth’s surfaee, irrespective of the climatic conditions there existing.

(2.) That during certain meteorological conditions,

mid-air explosions may result in rainfall over extended areas. (3.) That the liberation of energy necessary for such rainfalls is not due, except initially, to the mid-air ex- plosions, but to the energy stored up in the moist air from which the rain is derived.

(4.) That the meteorological conditions which must exist for the successful action of mid-air explosions would probably, in most though not in all cases, themselves result in a natural production of rain.

(5.) That a comparatively high difference of electric potential between different parts of the air or between the air and the earth is possibly favorable when taken in connection with other meteorological conditions for artificial rain making.

(6.) That an undirected mid-air explosion is not as likely to produce rain as an explosion in which