as well as many other special cars adapted to the needs of perishable freight. An hourly record is kept of the movements of the latter cars from the time they leave the consignor until they are delivered to the consignee. For every freight car moved a way bill is issued, which gives the number and owner of the car, a description of its contents, with the weight and address of every package, the names of the consignors and consignees, the starting-point and destination, charges, and every detail in regard to routes and the proportions of charges due the different car riers. Duplicates of these way bills go to the auditor's department, and from these the whole record of the freight business is made, and they are afterwards put on file for reference in case of claims. The average freight charges in this country are the cheapest in the world, yet the question of rates is the most troublesome one with which railway companies have to contend. The relative rates between different roads and different points rather than the actual charges for freight involve problems which railroad pools, traffic associations, and legislators have not been as yet entirely successful in solving. The subject is too broad to be discussed here, but two of the most important troubles in fixing rates lie in the discriminations in favor of large shippers and the reduction of through rates below those of intermediate points. Both of these practices, while apparently unfair to the public, are to some extent reasonable, as the same discrimination between large and small consumers is seen in the wholesale and retail prices in all businesses, and on some through lines, especially those in competition with water routes, the traffic must either be secured by special reduced rates between such points or be lost to the railways. Competition between railways is apparently less desirable than it is in the case of other kinds of trade, as the localities where it exists are alone benefited, and the business at other places is threatened. Railways serving a certain territory find it necessary to cooperate in fixing joint rates, and the concessions in charges which are mutually agreed upon between competing lines practically effect the same division of the traffic between them which was secured by the railway pools.

In making the rates, all articles of commerce are divided into several classes, and a certain standard rate per hundred pounds of each class is fixed between two important points, as New York and Chicago. Every other city reached by the same line is figured at its agreed proportion of the standard rates. For example: From New York to Pittsburg would be figured at 60 per cent. of the standard rate between New York and Chicago, and any change in the standard would affect all other places proportionately.

Mail service is a very important department of most railways from a public standpoint, although one which yields a comparatively small revenue to the railways in proportion to the service demanded. The present system of railway mail service was not suggested until 1862, and was not put into effect on a comprehensive scale until two years later, under the superintendence of Col. G. B. Armstrong. It was not, however, until about 1875 that special fast mail trains on which mail was sorted and distributed along the routes were put in operation. Special cars are provided for this service, which are fit

ted up with tables, pouches, and racks, and a 'mail catcher,' which picks up mail pouches from posts at stations where the train does not stop.

In 1900-1901 there were 9182 clerks employed in railway mail service in the United States, working in crews on 783,358 miles of railway. This number includes the clerks employed on steamboat lines (33,970 miles in length) and electric and cable cars. Considerable of the mail carried by the railways is charged at freight rates, according to its weight, and the larg est proportional earnings from this source are made by the railway companies which carry too little mail to warrant running high speed trains without extra remuneration. Considering the requirements of the mail service, which are met by the railway companies, the advantage of this traffic as a source of profit to them is doubtful. The time in transit for mail from New York to San Francisco, Cal., a distance of 3250 miles, is indicated by the Official Postal Guide as 106 hours; from New York to Chicago, 900 miles, 23 hours; New York to Buffalo, 410 miles, 91⁄2 hours, and New York to Albany, 142 miles, 3% hours.

RAILWAY CAPITALIZATION. Much of the financial difficulty under which a good many American railways have labored has been the direct outgrowth of speculation, in which the properties have frequently been practically wrecked merely to effect deals in the stock market, and roads which have been the subject of these operations are generally overcapitalized or mort gaged to such an extent that the earnings which would be sufficient to provide reasonable dividends on the actual value of the property are frequently too small to pay the interest on its bonds. The amount of railway stock which has been issued without consideration of money or value is unquestionably very large, although no approximation to the real sum is possible of being estimated. Occasionally such stock is issued pro rata to the stockholders of a very profit

able road to make the rate of dividends less

prominent, which might otherwise invite restrictive legislation. More frequently the object of issuing watered stock is to keep the control of the railway by means of the apparent investment it represents, or to balance some difference in cases of reorganization. The bonds represent very closely the amount of the debt actually paid in. The stockholders, as owners of the road, have the entire control of the property, and the bondholders have no voice in the management so long as their interest is paid. This condition, corresponding to that of the owners and mortgagees of real estate, is entirely reasonable as long as the actual investments in stock and bonds maintain normal proportions, for the reason that the stockholders assume all the risk, while the bondholders are practically secured. In some cases, however, the amount of money supplied by the stockholders is merely nominal, and the road is bonded for all or more than its value. This can only occur where the stock is most all 'water,' and its result is to put the management of the road in hands of parties having but little financial or other interest in it except for the opportunity it affords for speculating with the money of the bondholders. The abuses which have grown out of railway transactions under such circumstances constitute shameful chapters

in the history of a number of roads, such as the Erie, Wabash, Union Pacific, and others.

What are known as the Erie wars in 1868 illustrated the worst evils of this class. Two or three operators bought within a few weeks options on a large amount of Erie stock for the sum of $72,000, and obtained possession of sufficient proxies to elect one of their own representatives as president of the road. After thus obtaining control of the property, the railway was charged at once with the $72,000 spent in acquiring it, and the speculators then commenced selling the stock for a fall. This was eagerly purchased by the Erie's rivals, the owners of the New York Central road, and, instead of a fall, the price of Erie stock rose from 68 to about 80. As this threatened to ruin the Erie operators, they issued $5,000,000 worth of fraudulent stock, which was sold at 80, and on its discovery the speculators for a fall realized an enormous profit in addition to the $4,000,000 proceeds from the sale of fraudulent stock. In the legal proceedings which followed large sums of money were spent in buying up elections, legislatures, and judges, all of which were charged to the Erie road, and at the end of two or three years, when the ring lost its control, the indebtedness of the Erie had been increased by about $65,000,000, which prevented its stock from paying a dividend for twenty years.

A certain amount of hostile feeling has always existed between the public and the railways, which fortunately is diminishing with the better understanding of the questions in dispute. Practically the whole difference hinged on the matter of rates, and both sides have been at fault in treating this subject. The railways have at times made very unjust discriminations between different persons and different localities, and, on the other hand, the public in attempting to correct these abuses have passed laws which have been equally unjust to the railways. The problem of rates is an exceedingly difficult one to legislate upon, as no fixed rule can be justly applied in every case as to the proportional charges for different distances. A large proportion of the transportation of this country falls within the jurisdiction of the Interstate Commerce Law, which in respect to rates leaves considerable discretionary power in the hands of the Commission. See INTERSTATE COMMERCE

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ELEVATED RAILWAYS. Elevated railways is the name given to railways which run along a line of streets on girders supported on iron pillars erected on the street surface. The first elevated railway was a short line built in New York City in 1867, but the successful operation of such lines did not take place until 1872, when the New York Elevated Railroad Company began running trains on a line from Battery Park along Greenwich Street and Ninth Avenue to Thirtieth Street. From this time on the growth of the elevated railway system of New York was rapid, and succeeding years saw lines built in Brooklyn, Chicago, and Boston. Liverpool, Berlin, and Paris are among the foreign cities which possess elevated railway lines. The modern construction of elevated railways in America consists of steel pillars or columns erected along each curb line about 60 feet apart. The tops of these columns are connected across the street by plate girders (see BRIDGES), and these girders carry others generally one

under each track rail, reaching from one pair of columns to the next longitudinally of the street. The railway track is laid on these longitudinal girders, and consists of cross-ties with rails spiked to them in the usual manner. The stations are carried on elevated platforms level with the railway, and access and egress is had by means of stairways and elevators. On the Barmen-Elberfeld Railway, operated by electricity, the cars are suspended from the elevated structure. The principal elevated railway in Berlin is a viaduct of masonry, presenting fine architectural features.

MOUNTAIN RAILWAYS. The term mountain railway is applied to lines whose grades are too steep to be operated by locomotives, depending upon adhesion only for their drawing power, and which, therefore, necessitate the use of some special system of securing greater traction power. Several such systems are employed. The two principal ones are the Fell system, with a central, elevated, double-headed rail laid sideways, which is gripped by horizontal wheels on each side, which greatly augment the adhesion, and the system with central racks in which vertical cog-wheels work, whereby the adhesion of the ordinary driving wheels is greatly assisted in drawing a train up the incline, and the descent of the train is kept under control. This latter system embraces the Riggenbach, Abt, and other systems. In tourist lines ascending the steep sides of mountains for the sake of the views, a cog-wheel working in a central track is generally used as the sole means of propulsion up the inclines. Lastly, where the ascent is steep, straight, and fairly short, a cable is employed for hauling up the vehicles, resembling in principle the inclines worked by ropes in mines, a system which has also occasionally been adopted for the steep inclines on ordinary railways.

The central-rail system was first adopted for crossing the Mont Cenis Pass by a railway laid mainly along the road between Saint-Michel and Susa, a distance of 48 miles, having a gauge of 3 feet 7% inches and surmounting a difference of level of 5300 feet between Susa and the summit, with a total variation in level between its termini of about 9900 feet. The ruling gradient was 1 in 12, the average gradient about 1 in 17, and the central rail, raised 71⁄2 inches above the ordinary rail-level, was laid along all gradients exceeding 1 in 25; while the minimum radius -- 3′6′′ --

CENTRAL-RAIL SYSTEM FOR MOUNTAIN RAILWAYS.

for the curves was 2 chains. The greatest train load carried over the Mont Cenis Fell Railway was 36 tons, and the heaviest locomotives employed on it weighed 26 tons. In this system the grip of the horizontal wheel on the central rail not merely secures sufficient adhesion to mount steep inclines, but also serves as a very effective brake in the descent, and keeps the locomotive firmly on the line in going around sharp curves.

The Rimutaka incline, on the Wellington and Featherstone Railway in New Zealand, with a

gradient of 1 in 15 for 21⁄2 miles, and a total rise of 869 feet, opened about 1879, having a gauge, like the rest of the railway, of 3 feet 6 inches, and curves of 5 chains radius, was laid with a central rail, and the traffic on the incline has been worked continuously by a locomotive with horizontal wheels gripping the central rail. Each engine, weighing about 36 tons, can draw a maximum train load of 70 tons up the incline; and in order to avoid an undue strain on the draw-bars, the three engines employed for taking up a heavy train are so distributed between the carriages as to enable each to draw its own load. The system has proved safe and satisfactory, and well adapted for running around sharp curves; while the saving in cost of construction by adopting the incline on this particular railway, instead of a more circuitous course, to obtain flatter gradients, readily surmounted by ordinary locomotives, was estimated at £100,000.

A solid central rack was introduced for the first time in 1847 on an incline of the Madison and Indianapolis Railway near Madison, Ind. It was 1% miles long, with gradients of 1 in 162 to 1 in 17. The rack railway, however, which was the precursor of the numerous Swiss mountain railways for tourists, was the line, three miles in length, constructed up to the top of Mount Washington in New Hampshire in 186669, rising altogether to a height of 3600 feet, with ruling gradient of 1 in 3. The rack in this case was formed in lengths of 10 feet, with two parallel angle-irons, 4 inches apart, connected by a series of round wrought-iron bars constituting the teeth of the rack, which resembles a ladder laid on the ground. The locomotives, provided with a central cog-wheel working in the ladder-rack, push the vehicles up the mountain at a rate of about three miles an hour. The first rack railway carried out in Europe up a mountain slope was the Vitznau-Rigi Railway, constructed from Vitznau, on the Lake of Lucerne, to the summit of the Rigi in 1869-73, rising 4472 feet in its course of 43 miles, with a ruling gradient of 1 in 4 for about a third of its length, and never less than 1 in 6, except at the stations. The locomotive on these mountain lines is always placed below the carriages, so as to push them up the inclines and control their descent, the speed of the trains on the Rigi line being limited to between three and four miles an hour.

The driving cog-wheel and the other cog-wheels fitted to the locomotive and carriages are furnished with powerful brakes, which, when applied, keep the cogs firmly engaged in the rack, so as to arrest the descent of the train; and an air brake acting on the piston of the locomotive serves to regulate the downward speed. Strong hooks attached under the locomotive and carriages encircle the top flange of each side-piece of the rack, and thus secure the train from leaving the rails or being blown over by the wind.

A steel rack rail with teeth on each side, in which horizontal cog-wheels work, was adopted for surmounting the exceptionally steep inclines of the Pilatus Railway, averaging 1 in 2.8, and attaining 1 in 2.08 in some places, preliminary trials having proved that the ladder-rack was unsuitable for such gradients. This railway opened in 1889, starts from Alpnach on the Lake of Lucerne, and rises 5363 feet in its length of

24 miles. The driving cog-wheels are actuated by spur gearing, and the two pairs of cog-wheels are controlled by hand brakes, which suffice to regulate the descent of the train or to stop it if necessary. An air brake acting on the pistons of the locomotive furnishes additional control of the train on its descending journey; and if at any time the speed in descending becomes more than three miles an hour, a reserve automatic brake comes into action.

Another form of rack consists in cutting the edge of a flat steel bar, so as to provide a uniform row of teeth on its upper side, and the strength of the rack can be increased for steeper gradients by increasing the thickness or the number of the bars. The rack is thus formed by a series of solid bars, with teeth shaped to the most convenient form for the working of the cogwheel in them. This simple form of rack, consisting of successive lengths of single bars joined at their ends and laid in the centre of the track, has been employed on the flatter gradients of several rack railways, where the Abt system of two or more such bars, laid so that their teeth are not in line across the track, is resorted to on the steeper parts of the lines.

The Sant' Ellero-Saltino Railway, the first purely rack railway built in Italy, was constructed in 1892. This railway rises 2765 feet in a length of five miles, and it is laid to meter gauge, with a ruling gradient of 1 to 4.55. The rack on gradients not exceeding 1 in 8%, consists of two steel angle bars riveted together, 4 to 6 feet long, with teeth formed in them; but for steeper gradients up to the maximum of 1 in 4.55, two flat steel bars are introduced between the angle bars, increasing the thickness of the teeth and the rigidity of the rack, which latter can be still further augmented by introducing a distance piece between the angle bars, so as to form two or three parallel racks with a small interval between them, in which the cogwheel works with a widened bearing. This Telfener rack is simpler in construction and cheaper than the Riggenbach and Abt racks; but it does not possess the special advantage of the Abt rack, of thoroughly engaging two or three successive teeth of the cog-wheel at the same time. The speed of the trains ranges from 51⁄2 to 41⁄2 miles an hour, according to the gradients, and averages 5 miles an hour.

A more complicated form of single rack, resembling a flat-bottomed rail in its low portion, and widened out considerably for the teeth at

of 7 3-5 miles, with gradients ranging from 1 in 14% up to 1 in 5; and the upper 6 1-5 miles are to be in tunnel, while the final ascent to the summit is to be effected by a vertical lift of 241 feet. The central rack rails, 111⁄2 feet long, are joined together at their ends by fish-plates, like ordinary flat-bottomed rails." A brake is provided, which encircles and grips the widened-out head of the rack.

The Abt system consists essentially of two or three steel rack bars, from 11-16 inch to 1 13-16 inches thick, and 2 to 4% inches deep, placed nearly two inches apart, and so arranged that the teeth are not opposite each other, but as it were break joints, causing the cog-wheels to engage in a tooth in front on one rack before leaving the tooth behind on the adjacent rack, which renders the motion smoother, and increases the security of the trains in descending, besides proportioning the strength of the rack to the steepness of the gradient by the addition of one or two bars. The Generoso railway in Italy and the Rothorn railway in Switzerland, 5 2-3 miles and 4 4-5 miles long, rising 4326 feet and 5515 feet, with ruling gradients of 1 in 4.55 and 1 in 5, and constructed in 1889-90 and 1891, respectively, are laid to a gauge of 2 feet 7%1⁄2 inches with caststeel sleepers, and provided with a double Abt rack, in which cog-wheels on the driving axles work. The system has also been extended to mountain lines in several other countries, as, for instance, the Manitou and Pike's Peak Railway in Colorado, of standard gauge, rising 7552 feet in a length of 84 miles, with a maximum gradient of 1 in 4.

Instances of the application of electricity as the motive power on mountain railways laid with the Abt rack, where water-power is readily available for generating the electrical current, are furnished by the Mont Salève Railway near Geneva, and the Gornergrat Railway ascending from Zermatt. These railways, constructed in 1891 and 1896-98, respectively, have lengths of 53-5 miles and 54-5 miles, with rises of 2363 feet and 4600 feet, and are laid to the meter gauge, with gradients of 1 in 4 and 1 in 5, and a double line of rack. In all these rack railways, special care is always taken to anchor the track firmly down into the solid ground, so as to prevent its creeping gradually downhill under the pressure of the cog-wheels on the rack.

ELECTRIC RAILWAYS and STREET RAILWAYS will be found treated under their own heads. BIBLIOGRAPHY. Consult Poor's Manual of Railroads (New York, annual); Annual Reports of the Interstate Commerce Commission (Washington, D. C.); Hadley, Railway Transportation; Its History and Its Laws (New York, 1885). See LOCOMOTIVE;_ BLOCK SIGNAL SYSTEM; BRIDGE; AIR BRAKE; TUNNEL; etc.

RAILWAY TRAINMEN, BROTHERHOOD OF. See RAILWAY BROTHERHOODS.

RAIMONDI, ri-môn'dê, ANTONIO (1826-90). An Italian geographer and naturalist, born in Milan. In 1850 he went to Peru, and was professor of botany in the University of Lima from 1862 to 1871. During this time he explored the country and gathered material for his proposed exhaustive work on the geography, botany, zoology, and ethnology of Peru. Three volumes on geography were published (1874-76-80) and called El Perú, but a part of the work was destroyed when Lima was captured in the Chilean War, and Raimondi died before completing it. His manuscripts became the property of the Lima Geographical Society.

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RAIMONDI, MARCANTONIO (?-c.1534). chief Italian line engraver of the Renaissance. The year of his birth is unknown, but he was a native of Bologna, where he studied engraving under Francia, devoting himself at first to niello. him executing line engravings after the paintings At the beginning of the fifteenth century we find of Francia, but also after his own designs. Even in these early prints the influence of the German engravers, like Schongauer, is evident, particularly in the landscape backgrounds. Greatly impressed by Dürer's engravings, he copied about eighty of his woodcuts and copper plates in line engraving, even counterfeiting Dürer's signature. He thus pirated without acknowledgment the entire Life of the Virgin and the Little Passion. The generally accepted account, derived from Vasari, of how Dürer obtained redress from the Venetian Government is improbable, since the first series was not published until after Dürer's visit to Venice in 1506.

Until 1510 Raimondi resided at Bologna, with occasional visits to Venice, but in that year he seems to have been at Florence, since it was the date of his celebrated engraving, "Les grimpeurs," after Michelangelo's cartoon, the "Battle of Anghiari," the background of which was taken from Lucas van Leyden. He was then probably on the road to Rome, where he henceforth devoted himself to the reproduction of the works of Raphael. The latter even sketched designs for him, and himself added the finishing touches to the plates. Marcantonio carried out these designs with great vigor and charm, rendering, as no other has done, the forms of Raphael, not only in line, but in spirit. Among the best of his works executed after Raphael were: the "Murder of the Innocents;" "Quos Ego" (Neptune riding on a shell); "Lucretia;" the "Judgment of Paris;" "Adam and Eve;" etc. After Raphael's death he engraved after Giulio Romano, notably a "Bacchus and Ariadne;" and after the antique, which he was largely instrumental in popularizing. His engraving of Giulio's illustrations of Aretino's Sonnetti lussuriosi caused his imprisonment by Clement VII., and he was ruined by the sack of Rome in 1527, when he was held

for ransom by the Spaniards at an exorbitant sum. He returned to Bologna, where he died not later than 1534. The chief pupils of his school at Rome were Agostino Veneziano and Marco Dente of Ravenna. Consult Delaborde, MarcAntoine Raimondi (Paris, 1887).

RAIMUND, ri'munt, FERDINAND (1790-1836). An Austrian actor and playwright, born in Vienna. After playing on provincial stages in Hungary, he secured an engagement in Vienna at the Josephstädter Theatre in 1813, and in 1817 at the Leopoldstädter Theatre, where he soon became the most popular exponent of local comedy, and which he managed as director in 1828-30. In the meanwhile he had come before the public as a popular dramatist with Der Barometermacher auf der Zauberinsel (1823); Der Diamant des Geisterkönigs (1824); Der Bauer als Millionär (1826); Alpenkönig und Menschenfeind (1828); and others which, after severing his connection with the Leopoldstädter Theatre, he mounted on the stages of Munich, Hamburg, and Berlin, appearing himself in them in a starring capacity. His last and best play was Der Verschwender (1833), which is still popular on the German stage. In a fit of hypochondria Raimund attempted his life with a pistol and died within a week on his little estate of Gutenstein. He was a genuine poet in the popular vein, who dwelt with affectionate sympathy upon the life of the people, and weaved its joys and sorrows into the fabric of fantastic Their pathos and dramas of peculiar charm. humor are alike telling. His life was made the subject of a novel by Otto Horn (Bäuerle) and of several dramatic productions. By the Raimund Dramatic Club, founded in Vienna in 1890, the Raimund Theatre was established there in 1893. RAIMUND, GOLO. The pseudonym of the German novelist Bertha Frederich (q.v.).

RAIN (AS. regn, ren, Goth. rign, OHG. regan, Ger. Regen, rain; connected with Lat. rigare, Gk. Bpéxe, brechein, to wet). Drops of water formed in the atmosphere by the condensation of its aqueous vapor and falling rapidly by virtue of their weight: the very small drops that fall slowly are spoken of as mist, cloud, or fog. The largest drops of rain that have been measured are as much as 0.25 to 0.30 inch in diameter and fall at the rate of from 15 to 25 feet per second. The smallest drops that are likely to be spoken of as rain are about one-twentieth of an inch in diameter and fall at the rate of about five feet per second. As rain water is condensed vapor that had previously been evaporated from distant water surfaces, therefore, in accordance with the laws of evaporation, it would be chemically pure water were it not for a small percentage of foreign substance which it gathers to itself from the atmosphere. Rain water washes down out of the air dust, soot, pollen, spores of fungi, and many other solid substances. Ordinary rain water contains an appreciable percentage of dissolved oxygen, nitrogen, ammonia, and carbonic acid gas, and in special cases it is found to contain nitric acid, sulphuric acid, and other components of the impure air of cities. The acid and alkaline impurities generally increase the power of the rain water to dissolve the mineral constituents of the earth's crust; the gases make it possible for plants and animals to live in rivers and ponds, which would be impossible if the water were

chemically pure. Rain water only becomes wholesome potable water for man's use after it has been thoroughly filtered through the earth, whence it issues as springs of pure water.

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Up to the middle of the nineteenth century rain was supposed to be naturally formed by the mixture of cold and warm masses of moist air, but the publication of Espy's Philosophy of Storms (Boston, 1842), and his life-long contention that cloud and rain are not due to cooling by mixture or by radiation, but are a consequence of the cooling of the atmosphere by virtue of the work done in expansion, supported as he was by Professor Joseph Henry, Sir William Thom(Lord Kelvin), and other physicists, finally meteorologists to study the great thermodynamic problems of the atmosphere. is forcibly compressed, the work done by compression sented by the increase in temperature of the confined air; vice versa when the air expands by diminution of pressure, the work done in expansion is represented by the heat abstracted from the expanding air,which therefore experiences a corresponding cooling. The laws of convective equilibrium governing the temperature and the volume of a unit mass of rising air were first expressed in the exact language of mathematical physics by Sir William Thomson in Graphic methods of treating the complex meteorological problems were devised by Hertz in 1884, and improved by Von Bezold in 1888 and Neuhoff in 1900. The analytical treatment of the subject is given by F. H. Bigelow with convenient tables in his report of 1900 On the International Observations of Clouds. When warm moist air ascends from near the earth's surface it cools by expansion; if no heat is added or subtracted, it is said to cool adiabatically, and does so at the rate of about one degree Centigrade per 99 meters of ascent, or one degree Fahrenheit for 185 feet, until it reaches an altitude at which its temperature is the same as the temperature of the dew point of the original air. `At and above this elevation cloud is formed as the air ascends. If the rise continues until the air has cooled to the temperature of freezing point of water, then the watery cloud particles begin to change to ice, giving out a little of their latent heat as they do so. When in the course of its further ascent all the cloud particles have become ice, then any additional rise will be accompanied by the formation of snow crystals. This latter condition would continue to exist throughout the further ascent of the air were it not that in these higher regions the formation of snow is very slight. If the sun is shining upon the clouds, the process ceases to be adiabatic, and the particles of water or ice may be immediately evaporated back into vapor. Owing to the resistance of the air, the cloud particles fall very slowly to the ground, or may, in fact, be upheld indefinitely by a gentle ascending current. But if numerous small particles combine together into drops of water, the latter may fall rapidly to the ground as rain. The above paragraph correctly explains the formation of cloud by cooling due to expansion, but nothing is as yet known satisfactorily as to the process by which large raindrops are formed from the minute cloud particles.

Among the several plausible hypotheses are the following: (a) That the cloud particles are