Chapter 2

His contribution to the theory of the velocity of sound in air was likewise of great importance, and is distinguished alike for the acuteness of his explanations of the existing causes of error in the work of previous experimenters, and for the accuracy, so far as was required for the purpose in hand, of his own experiments. His determination of the specific heat of air, pressure constant, and the specific heat of air, volume constant, furnished the data necessary for making Laplace's theoretical velocity agree with the velocity of sound experimentally determined. On the other hand, he was able to account for most puzzling discrepancies, which appeared in attempted direct determinations of the differences between the two specific heats by careful experimenters. He pointed out that in experiments in which air was allowed to rush violently or _explode_ into a vacuum, there was a source of loss of energy that no one had taken account of, namely, in the sound produced by the explosion. Hence in the most careful experiments, where the vacuum was made as perfect as possible, and the explosion correspondingly the more violent, the results were actually the worst. With his explanations, the theory of the subject was rendered quite complete.

Space fails, or I should mention in detail Mr. Joule's experiments on magnetism and electro-magnets, referred to at the commencement of this sketch. He discovered the now celebrated change of dimensions produced by the magnetization of soft iron by the current. The peculiar noise which accompanies the magnetization of an iron bar by the current, sometimes called the "magnetic tick," was thus explained.

Mr. Joule's improvements in galvanometers have already been incidentally mentioned, and the construction by him of accurate thermometers has been referred to. It should never be forgotten that _he first_ used small enough needles in tangent galvanometers to practically annul error from want of uniformity of the magnetic field. Of other improvements and additions to philosophical instruments may be mentioned a thermometer, unaffected by radiation, for measuring the temperature of the atmosphere, an improved barometer, a mercurial vacuum pump, one of the very first of the species which is now doing such valuable work, not only in scientific laboratories, but in the manufacture of incandescent electric lamps, and an apparatus for determining the earth's horizontal magnetic force in absolute measure.

Here this imperfect sketch must close. My limits are already passed. Mr. Joule has never been in any sense a public man; and, of those who know his name as that of the discoverer who has given the experimental basis for the grandest generalization in the whole of physical science, very few have ever seen his face. Of his private character this is scarcely the place to speak. Mr. Joule is still among us. May he long be spared to work for that cause to which he has given his life with heart-whole devotion that has never been excelled.

In June, 1878, he received a letter from the Earl of Beaconsfield announcing to him that Her Majesty the Queen had been pleased to grant him a pension of £200 per annum. This recognition of his labors by his country was a subject of much gratification to Mr. Joule.

Mr. Joule received the Gold Royal Medal of the Royal Society in 1852, the Copley Gold Medal of the Royal Society in 1870, and the Albert Medal of the Society of Arts from the hand of the Prince of Wales in 1880.

J. T. BOTTOMLEY.

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THE NEW YORK CANALS.

The recent adoption of the constitutional amendment abolishing tolls on the canals of New York State has revived interest in these water ways. The overwhelming majority by which the measure was passed shows, says the _Glassware Reporter_, that the people are willing to bear the cost of their management by defraying from the public treasury all expenses incident to their operation. That the abolition of the toll system will be a great gain to the State seems to be admitted by nearly everybody, and the measure met with but little opposition except from the railroad corporations and their supporters.

At as early a date as the close of the Revolutionary War, Mr. Morris had suggested the union of the great lakes with the Hudson River, and in 1812 he again advocated it. De Witt Clinton, of New York, one of the most, valuable men of his day, took up the idea, and brought the leading men of his State to lend him their support in pushing it. To dig a canal all the way from Albany to Lake Erie was a pretty formidable undertaking; the State of New York accordingly invited the Federal government to assist in the enterprise.

The canal was as desirable on national grounds as on any other, but the proposition met with a rebuff, and the Empire State then resolved to build the canal herself. Surveyors were sent out to locate a line for it, and on July 4, 1817, ground was broken for the canal by De Witt Clinton, who was then Governor of the State.

The main line, from Albany, on the Hudson, to Buffalo, on Lake Erie, measures 363 miles in length, and cost $7,143,789. The Champlain, Oswego, Chemung, Cayuga, and Crooked Lake canals, and some others, join the main line, and, including these branch lines, it measures 543 miles in length, and cost upward of $11,500,000. This canal was originally 40 feet in breadth at the water line, 28 feet at the bottom, and 4 feet in depth. Its dimensions proved too small for the extensive trade which it had to support, and the depth of water was increased to 7 feet, and the extreme breadth of the canal to 60 feet. There are 84 locks on the main line. These locks, originally 90 feet in length and 15 in breadth, and with an average lift of 8 feet 2 inches, have since been much enlarged. The total rise and fall is 692 feet. The towpath is elevated 4 feet above the level of the water, and is 10 feet in breadth. At Lockport the canal descends 60 feet by means of 5 locks excavated in solid rock, and afterward proceeds on a uniform level for a distance of 63 miles to the Genesee River, over which it is carried on an aqueduct having 9 arches of 50 feet span each. Eight and a half miles from this point it passes over the Cayuga marsh, on an embankment 2 miles in length, and in some places 70 feet in height. At Syracuse, the "long level" commences, which extends for a distance of 69½ miles to Frankfort, without an intervening lock. After leaving Frankfort, the canal crosses the river Mohawk, first by an aqueduct 748 feet in length, supported on 16 piers, elevated 25 feet above the surface of the river, and afterward by another aqueduct 1,188 feet in length, and emerges into the Hudson at Albany.

This great work was finished in 1825, and its completion was the occasion of great public rejoicing. The same year that the Erie Canal was begun, ground was broken for a canal from Lake Champlain to the Hudson, sixty-three miles in length. This work was completed in 1823.

The construction of these two water ways was attended with the most interesting consequences. Even before they were completed their value had become clearly apparent. Boats were placed upon the Erie Canal as fast as the different levels were ready for use, and set to work in active transportation. They were small affairs compared with those of the present day, being about 50 or 60 tons burden, the modern canal boat being 180 or 200 tons. Small as they were, they reduced the cost of transportation immediately to one-tenth what it had been before. A ton of freight by land from Buffalo to Albany cost at that time $100. When the canal was open its entire length, the cost of freight fell from fifteen to twenty-five dollars a ton, according to the class of article carried; and the time of transit from 20 to 8 days, Wheat at that time was worth only $33 a ton in western New York, and it did not pay to send it by land to New York. When sent to market at all, it was floated down the Susquehanna to Baltimore, as being the cheapest and best market. The canal changed that. It now became possible to send to market a wide variety of agricultural produce--fruit, grain, vegetables, etc.--which, before the canal was built, either had no value at all, or which could be disposed of to no good advantage. It is claimed by the original promoters of the Erie Canal, who lived to see its beneficial effects experienced by the people of the country, that their work, costing less than $8.000,000 and paying its whole cost of construction in a very few years, added $100,000,000 to the value of the farms of New York by opening up good and ready markets for their products. The canal had another result. It made New York city the commercial metropolis of the country. An old letter, written by a resident of Newport, R. I., in that age, has lately been discovered, which speaks of New York city, and says: "If we do not look out, New York will get ahead of us." Newport was then one of the principal seaports of the country; it had once been the first. New York city certainly did "get ahead of us" after the Erie Canal was built. It got ahead of every other commercial city on the coast. Freight, which had previously gone overland from Ohio and the West to Pittsburg, and thence to Philadelphia, costing $120 a ton between the two cities named, now went to New York by way of the Hudson River and the Erie Canal and the lakes. Manufactures and groceries returned to the West by the same route, and New York became a flourishing and growing emporium immediately. The Erie Canal was enlarged in 1835, so as to permit the passage of boats of 100 tons burden, and the result was a still further reduction of the cost of freighting, expansion of traffic, and an increase of the general benefits conferred by the canal. The Champlain Canal had an effect upon the farms and towns lying along Lake Champlain, in Vermont and New York, kindred in character to that above described in respect to the Erie Canal. It brought into the market lands and produce which before had been worthless, and was a great blessing to all concerned.

There can be no doubt that the building of the Erie Canal was the wisest and most far-seeing enterprise of the age. It has left a permanent and indelible mark upon the face of the republic of the United States in the great communities it has directly assisted to build up at the West, and in the populous metropolis it created at the mouth of the Hudson River. None of the canals which have been built to compete with it have yet succeeded in regaining for their States what was lost to them when the Erie Canal went into operation. This water route is still the most important artificial one of its class in the country, and is only equaled by the Welland Canal in Canada, which is its closest rival. Now that it is free, it will retain its position as the most popular water route to the sea from the great West. The Mississippi River will divert from it all the trade flowing to South America and Mexico; but for the northwest it will be the chief water highway to the ocean.

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COTTRAU'S LOCOMOTIVE FOR ASCENDING STEEP GRADES.

We borrow, from our contemporary _La Nature_, the annexed figure, illustrating an ingenious type of locomotive designed for equally efficient use on both level surfaces and heavy grades.

As well known, all the engines employed on level roads are provided with large driving wheels, which, although they have a comparatively feeble tractive power, afford a high speed, while, on the contrary, those that are used for ascending heavy grades have small wheels that move slowly, but possess, as an offset, a tractive power that enables them to overcome the resistances of gravity.

M. Cottrau's engine possesses the qualities of both these types, since it is provided with wheels of large and small diameter, that may be used at will. These two sets of wheels, as may be seen from the figure, are arranged on the same driving axle. The large wheels are held apart the width of the ordinary track, while the small wheels are placed internally, or as in the case represented in the figure, externally. These two sets of wheels, being fixed solidly to the same axle, revolve together.

On level surfaces the engine rests on the large wheels, which revolve in contact with the rails of the ordinary track, and it then runs with great speed, while the auxiliary wheels revolve to no purpose. On reaching an ascent, on the contrary, the engine meets with an elevated track external or internal to the ordinary one, and which engages with the auxiliary wheels. The large wheels are then lifted off the ordinary track and revolve to no purpose. In both cases, the engine is placed under conditions as advantageous as are those that are built especially for the two types of roads. The idea appears to be a very ingenious one, and can certainly be carried out without disturbing the working of the locomotive. In fact, the same number of piston strokes per minute may be preserved in the two modes of running, so as to reduce the speed in ascending, in proportion to the diameters of the wheels. There will thus occur the same consumption of steam. On another hand, there is nothing to prevent the boiler from keeping up the same production of steam, for it has been ascertained by experience, on the majority of railways, that the speed of running has no influence on vaporization, and that the same figures may be allowed for passenger as for freight locomotives.

The difficulties in the way of construction that will be met with in the engine under consideration will be connected with the placing of the double wheels, which will reduce the already limited space at one's disposal, and with the necessity that there will be of strengthening all the parts of the mechanism that are to be submitted to strain.

The installation of the auxiliary track will also prove a peculiarly delicate matter; and, to prevent accidents, some means will have to be devised that will permit the auxiliary wheels to engage with this track very gradually. Still, these difficulties are perhaps not insurmountable, and if M. Cottrau's ingenious arrangement meets with final success in practice, it will find numerous applications.

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BACHMANN'S STEAM DRIER.

The apparatus shown in the annexed cuts is capable of effecting a certain amount of saving in the fuel of a generator, and of securing a normal operation in a steam engine. If occasion does not occur to blow off the motive cylinder frequently, the water that is carried over mechanically by the steam, or that is produced through condensation in the pipes, accumulates therein and leaks through the joints of the cocks and valves. This is one of the causes that diminish the performance of the motor.

The steam drier under consideration has been devised by Mr. Bachmann for the purpose of doing away with such inconveniences. When applied to apparatus employed in heating, for cooking, for work in a vacuum, it may be affixed to the pipe at the very place where the steam is utilized, so as to draw off all the water from the mixture.

As shown by the arrows in Fig 1, the steam enters through the orifice, D, along with the water that it carries, gives up the latter at P, and is completely dried at the exit, R. The partition, g, is so arranged as to diminish the section of the steam pipe, in order to increase the effect of the gravity that brings about the separation of the mixture. The water that falls into the space, P, is exhausted either by means of a discharge cock (Fig. 1), which gives passage to the liquid only, or by the aid of an automatic purge-cock (Figs. 2 and 3), the locating of which varies with the system employed. This arrangement is preferable to the other, since it permits of expelling the water deposited in the receptacle, P, without necessitating any attention on the part of the engine-man.

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H.S. PARMELEE'S PATENT AUTOMATIC SPRINKLER.

The inventor says: "The automatic sprinkler is a device for automatically extinguishing fires through the release of water by means of the heat of the fire, the water escaping in a shower, which is thrown in all directions to a distance of from six to eight feet. The sprinkler is a light brass rose, about 1½ inches diameter and less than two inches high entire, the distributer being a revolving head fitted loosely to the body of the fixed portion, which is made to screw into a half inch tube connection. The revolution of the distributer is effected by the resistance the water meets in escaping through slots cut at an angle in the head. The distribution of water has been found to be the most perfect from this arrangement. Now, this distributing head is covered over with a brass cap, which is soldered to the base beneath with an alloy which melts at from 155 to 160 degrees. No water can escape until the cap is removed. The heat of an insignificant fire is sufficient to effect this, and we have the practical prevention of any serious damage or loss through the multiplication of the sprinkler.

The annexed engravings represent the sprinkler at exact size for one-half inch connection. Fig. 1 shows a section with the cap covering over the sprinkler, and soldered on to the base. Fig. 2 shows the sprinkler with the cap off, which, of course, leaves the water free to run from the holes in fine spray in all directions. Fig. 1 shows the base hollowed out so as to allow the heat to circulate in between the pipe and the base of the sprinkler, thus allowing the heat to operate on the _inside_ as well as on the outside of the sprinkler; thus, in case of fire, it is very quickly heated through sufficiently to melt the fusible solder. These sprinklers are all tested at 500 lb., consequently they can never leak, and cannot possibly be opened, except by heat, by any one. As the entire sprinkler is covered by a heavy brass cap, soldered on, it cannot by any means be injured, nor can the openings in the revolving head ever become filled with dust.

It is so simple as to be easily understood by any one. As soon as the sprinkler becomes heated to 155 degrees, the cap will become unsoldered, and will then immediately be blown entirely off by the force of the water in the pipes and sprinkler. These caps cannot remain on after the fusible metal melts, if there is the least force of water. A man's breath is sufficient to blow them off.

The arrangement commences with one or more main supply pipes, either fed from a city water pipe or from a tank, as the situation will admit. If desired, the tank need only be of sufficient size to feed a few sprinklers for a short time, and then dependence must be placed upon a pump for a further supply of water, if necessary. The tank, however small, will insure the automatic and prompt working of the sprinklers and alarm, and by the time the tank shall become empty the pumps can be got at work. It is most desirable, however, in all cases to have an abundant water supply without resorting to pumps, if it is possible.

In the main supply pipe or pipes is placed our patent alarm valve, which, as soon as there is any motion of the water in the pipe, opens, and moves a lever, which, by connecting with a steam whistle valve by means of a wire, will blow the whistle and will continue to do so until either the steam or the water is stopped. Tins constitutes the alarm, and is positive in its motion. No water can possibly flow from the line of pipes without opening this valve and blowing the whistle. We also put in an automatic alarm bell when desired.

From the main pipe other pipes are run, generally lengthways of the building, ten feet from each side and twenty feet apart. At every ten feet on these pipes we place five feet of three-quarter inch pipe, reaching each side, at the end of which is placed the sprinkler in an elbow pointing toward the ceiling. This arrangement is as we place them in all cotton and woolen mills, but may be varied to suit different styles of buildings.

The sprinkler is made of brass, and has a revolving head, with four slots, from which the water flies in a very fine and dense spray on everything, and filling the air very completely for a radius of seven or eight feet all around; thus rendering the existence of any fire in that space perfectly impossible; and as the sprinklers are only placed ten feet apart, and a fire cannot start at a greater distance than from five to six feet from one or more of them, it is assured that all parts of a building are fully protected.

Over each one of these sprinklers is placed a brass cap, which fits closely over and passes below the base, where it is soldered on with a fusible metal that melts as soon as it is heated to 155 degrees.

As soon as a fire starts in any part of a building, heat will be generated and immediately rise toward the ceiling, and the sprinkler nearest the fire will become heated in a very few moments to the required 155 degrees, when the cap will become loosened and will be forced off by the power of the water. The water will then be spread in fine spray on the ceiling over the fire, also directly on the fire and all around for a diameter of from fourteen to eighteen feet. This spray has been fully tried, and it is found to be entirely sufficient to extinguish any fire within its reach which can be made of any ordinary materials.

As soon as the cap on any sprinkler becomes loosened by the heat of a fire and is forced off, a current of water is produced in the main pipe where the alarm valve is placed, and as the passage through it is dosed, the water cannot pass without opening the valve and thus moving the lever to which the steam whistle valve is attached; by this motion the whistle valve is opened, and the whistle will blow until it is stopped by some one."

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INSTRUMENT FOR DRAWING CONVERGING STRAIGHT LINES.

[Footnote: Paper by Prof. Fr. Smigaglia, read at the reunion of the Engineers and Architects of Rome.]

1. LET A and B be two fixed points and A C and C B two straight lines converging at C and moving in their plane so as to always remain based on this point (Fig. 1). The geometrical place of the positions occupied by C is the circumference of the circle which passes through the three points A, B, and C. Now let C F be a straight line passing through C. On prolonging it, it will meet the circumference A C B I at a point I. If the system of three converging--lines takes a new position A C' F B, it is evident F' B' prolonged will pass through I, because the angles [alpha] and [beta] are invariable for any position whatever of the system.

2. In the particular case in which [alpha] = [beta] (Fig. 2), the point I is found at the extremity of the diameter, and, consequently, for a given distance A B, or for a given length C D, such point will be at its maximum distance from C.

3. This granted, it is easy to construct an instrument suitable for drawing converging lines which shall prove useful to all those who have to do with practical perspective. For this purpose it is only necessary to take three rulers united at C (Fig. 3), to rest the two A C and C B against two points or needles A and B, and to draw the lines with the ruler C F, in placing the system (§ 1) in all positions possible. The three rulers may be inclined in any way whatever toward each other, but (§ 2) it is preferable to take the case where [alpha] = [beta].