Chapter 7

The main object of this present paper is to deal with the advantages of the valve gear and its application to various classes of engines both on land and at sea, and with the results of such applications, rather than treating it as a novelty, to give an exhaustive description of its construction and functions, which was done in the paper above referred to. A very short description of its action and main features will, however, be necessary to the completeness of the paper, and as a basis from which the improved results to be recorded should necessarily be shown to spring.

The essential feature of this valve gear is that movement for the valve is produced by a combination of two motions at right angles to each other; and by the various proportions in which these are combined, and by the positions in which the moving parts are set with regard to each other, it gives both the reversal of motion and the various degrees of expansion required. Eccentrics are entirely dispensed with and the time-honored link gear abandoned, the motion is taken direct from the connecting rod, and by utilizing independently the backward and forward action of the rod, due to the reciprocation of the piston, and combining this with the vibrating action of the rod, a movement results which is suitable to work the valves of engines, allowing the use of any proportions of lap and lead desired, and giving an almost mathematically correct "cut-off" for both sides of the piston and for all points of expansion intermediately, as well as a much quicker action at the points of "cut-off" and "release" than is given by a link gear.

The machinery for accomplishing this is both less costly and less complicated than the ordinary link motion, and is shown in elevation on cut, which is a view of the complete motion as on the first London and North-Western locomotive. Here E is the main valve lever, pinned at D to a link, B, one end of which is fastened to the connecting rod at A, and the other end maintained in about the vertical by the radius rod, C, which is fixed at the point, C¹. The center or fulcrum, F, of the lever, E, partaking of the vibrating movement of the connecting rod at the point, A, is carried in a curved slide, J, the radius of which is equal to the length of the link, G, and the center of which is fixed to be concentric with the fulcrum, F, of the lever when the piston is at either extreme end of its stroke. From the upper end of the lever, E, the motion is carried direct to the valve by the rod, G. It will be evident thus that by one revolution of the crank the lower end of the lever, E, will have imparted to it two different movements, one along the longer axis of the ellipse, traveled by the point, A, and one through its minor axis up and down, these movements differing as to time, and corresponding with the part of the movement of the valve required for lap and lead, and that part constituting the port opening for admission of steam.

The former of these is constant and unalterable, the latter is controllable by the angle at which the curved slide, J, may be set with the vertical.

It will further be evident that if the lever, E, were pinned direct to the connecting rod at the point, A, which passes through a practically true ellipse, it would vibrate its fulcrum, F, unequally on either side of the center of the curved slide, J, by the amount of the versed sine of the arc of the lever, E, from F D; it is to correct this error that the lever, E, is pinned at the point, D, to a parallel motion formed by the parts, B and C. The point, D, performing a figure which is equal to an ellipse, with the error to be eliminated added, so neutralizing its effect on the motion of the fulcrum, F.

The "lap" and "lead" are opened by the action of the valve lever acting as a lever, and the port opening is given by the incline of the curved slide in which the center of that lever slides, and the amount of this opening depends upon the angle given to that incline. When these two actions are in unison, the motion of the valve is very rapid, and this occurs when the steam is being admitted. Then follows a period of opposition of these motions, during which time the valve pauses momentarily, this corresponding to the time when the port is fully open. Further periods of unison follow, at which time the sharp "cut-off" is obtained.

The "compression" resulting with this gear is also reduced to a minimum, owing to the peculiar movement given to the valves (_i. e._, the series of accelerations and retardations referred to), as, while the "lead" is obtained later and quicker, the port is also shut for "compression" later and quicker, doing away with the necessity for a special expansion valve, with its complicated and expensive machinery, and allowing the main valve to be used for expansion, as the "compression" is not of an injurious amount, even with a "cut-off" reduced to 15 per cent., or about 1/6 of the stroke.

Thus, so far as the distribution of the steam and its treatment in the cylinder is concerned, a marked advantage is shown in favor of this valve gear. But next in its favor, as before said, is that the above advantages are not gained at the cost of added complication of parts or increased cost of machinery, but the reverse, as this gear can be built at a less cost than link gear, varying according to the circumstances, but reaching as high as a saving of 25 per cent., or, if it be compared with a link gear supplemented by the usual special expansion valve and gear as employed on marine engines, then the total saving is fully 50 per cent., and an equally good result is obtained as to the distribution and subsequent treatment of the steam.

After accuracy of result and reduction in cost may rank saving room and the advantages arising therefrom (though for steamships perhaps this should have come first). Taking locomotives of the inside cylinder type, which is the general form in use in England and the continent of Europe, by clearing away the eccentrics and valves from the middle of the engine, much larger cylinders may be introduced and a higher rate of expansion employed, and this is being done. Also room is left for increasing the length and wearing surfaces of all the main bearings with even less crowding than is now the case with engines with the smaller cylinders.

But this advantage of saving room comes much more prominently forward in marine engines, especially in war ships, where every inch of room saved is valuable; and in the new type of triple-cylinder engines now coming so much into vogue in the mercantile marine, whether those engines be only the ordinary three-cylinder engines with double expansion, or the newer, triple expansion engine, expanding the steam consecutively through three cylinders--the form of marine engine which promises to come into use wherever high-class work and economy are required. On this system, by placing all the valve chests in front of the cylinders instead of between them, or in a line with them, sufficient room is saved to get the new-type three-cylinder engine into the space occupied by the old form of two-cylinder engine.

Besides these prominent advantages there are others which, though of minor importance, are still necessary to the practical and permanent success of any new mechanical arrangement, such as the accessibility of all the working parts while in motion, for examination and oiling; the ease with which any part or the whole can be stripped and cleaned, or pinned up out of the way in case of break down or accident, or got at and dismantled for ordinary repair; the ease with which the whole may be handled, started, reversed, or set at any point of expansion--all these being recommendations to enlist the care and attention of the engineers in charge by lightening their duties and rendering the engines easy to work.

With those advantages it is perhaps not surprising that this valve gear has been very considerably adopted for many classes of steam engines, especially where a high result has been required, with economy of space, and a minimum of complication.

Having crucially tested the original engine on the London and North-Western Railway, Mr. Webb proceeded to build others similar, and on his bringing out his Compound Express Engine--notably the most advanced step in locomotive design of the present day--he adopted this valve gear throughout. There are now a number of these engines running some of the fastest trains on the London and North-Western Railway, with the most satisfactory results.

Following these, others of the leading railways took up the system, and prominently among these Mr. Worsdell, of the Great Eastern Railway, built a number of large express engines for his fast and heavy traffic, and is now building a number of others similar as to the valve gear for his suburban traffic, which is specially heavy. Also the Lancashire and Yorkshire and the Midland and others of the chief railways are employing the system specially for large express engines; the Midland engines having cylinders of 19 inches diameter by 26 inches stroke, and four coupled wheels of 7 feet diameter. A number of the above-named engines have run large mileages, in many cases already exceeding 100,000 miles per engine. For other countries also a number of locomotive engines have been built or contracted for--both of inside and outside cylinder types--making a total of nearly 800 locomotives built and building, many of them being of special design and large size, up to 20 inches and 21 inches diameter of cylinder.

In all these the absence of wire-drawing may be specially noted by the full line at the top of the diagram, showing the admission of steam--this fullness arising from the rapid and full opening of the port for admission.

Passing now to the other great type of engines, those covered under the general designation of marine engines, this gear has been applied to nearly 40,000 H.P. indicated, built and building, and to all classes and sizes, from the launch engine with cylinders 8 inches by 9 inches, running at 600 to 700 revolutions per minute, up to engines for the largest class of war ships, such as her Britannic Majesty's steel cruiser Amphion, of 5,000 H.P., with cylinders in duplicate of 46 inches and 86 inches diameter, and 3 feet 3 inches stroke, running 100 revolutions per minute. An examination of the indicator diagrams taken from these engines shows that no wire-drawing takes place, and that, though the expansion is carried to a point beyond the ordinary requirements, the compression is but slightly increased. In all the diagrams taken from this valve motion there is seen the clear, full upper line showing an abundant admission of steam without any wire-drawing, and also the distinctly marked points where "cut-off" or "suppression" and where "release" takes place, showing the rapid action of the valves at those points.

It is well known to engineers that to obtain the maximum advantage out of compounding, it is necessary to cut off in the low pressure cylinder at a point corresponding to the relation between the low and the high, and that point should be unaltered, whereas the point of cut-off in the high may at the same time be varied to suit the work to be done.

In an ordinary link motion engine (where both links are connected to the same weigh shaft), when linking up the high pressure cylinder to cut-off short, the same change is necessarily made in the low. By the use of the Joy gear, cut-off valves may be fitted to both cylinders, that for the low pressure being fixed at the constant position required by the proportion of the cylinders, while that on the high is adjustable; of course, in this case, the position of the quadrants must be only changed for reversing. In arranging the independent cut-off on the Joy gear, it is only necessary to increase the length of the vibrating link beyond the point of attachment for the main valve spindle connection to obtain a point from which motion may be taken to actuate the cut-off valve; even then the cost of the Joy gear for both cylinders is but little more than for a single set of link gear.

This arrangement gives an absolutely perfect distribution of steam for compounding, also equalizes the power developed by both cylinders, and is far more simple and inexpensive than any other gear in existence.

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THE STEAM BELL.

The secondary railways in rural districts in Austria having no gates or bars at the level crossings, or guards at such points, but being open like tramways, special precautions are required to avoid accidents, and the public has to be warned of the approach of the train from a sufficient distance. This is done by ringing bells preferably to sounding whistles, as these are more likely to startle horses. The steam bell shown by our illustrations has been adopted for this purpose on the Austrian lines, and is a simple contrivance. It consists of a cylindrical chamber, a, ending in a narrower tube, c, which forms the seating for a flap valve, d, to which the hammer or clapper, e, is fixed. Steam is admitted through a small pipe, b, at the bottom, and after a certain interval attains sufficient pressure to lift the valve. The opening being large compared with the pipe, b, steam escapes more rapidly than it arrives through the small orifice; the pressure falls, and the valve drops down and causes the hammer to strike a bell surrounding the cylinder. The valve is provided with an internal collar as shown, so that it has to rise for the width of this before the steam is let out, and thus determines the swing of the clapper and the force of the blow. To intensify the latter and multiply the number of blows, the clapper spring is prolonged over the fulcrum and bent back so as to form a spring, which is tightened by the lifting of the flap, and sends the clapper down on the bell with increased force. The hinge of the flap does not require any lubrication besides what it gets through the steam. The bell is fixed upon the roof of the driver's cab, so that the steam does not interfere with his lookout, and fastened by three bolts or screws. The diameter of the steam-pipe is from ¼ to ½ inch according to the size of the bell, and the distance of the clapper from the bell is a little less than the diameter of the corresponding cock. The steam cock is perforated as shown by the illustration to drain the pipe when shut, and a small hole, b¹, in the bell cylinder drains the latter. The steam-pipe is made with a bend as usual, to allow for contraction and expansion. The number of blows given varies according to the steam pressure, and the opening of the steam cock; it is

With 90 lb. pressure, and cock 1/2 open, 170 blows per min. " " " " 1/3 " 136 " 105 " " " 1/2 " 240 " " " " " 1/3 " 156 " " " " " 1/5 " 136 " 120 " " " 1/3 " 228 " 135 " " " 1/5 " 200 "

To start the bell, the cock is opened full, and afterward partly closed. The blows follow in such rapid succession that a kind of uniform sound with louder intervals is produced, but not of the same shrill character as by a steam whistle. The same kind of bell is used on the shunting engines in goods yards, where roadways have to be crossed on which lurries and handtrucks circulate, and the results as far as prevention of accidents is concerned are stated to be very satisfactory.

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LIEUT. GREELY BEFORE THE BRITISH ASSOCIATION.

Lieuts. Greely and Ray were received with distinguished honors at the meeting of the British Association in Montreal. A complimentary luncheon was tendered him by the members of the British Association for the Advancement of Science, at the Windsor Hotel. General Sir Henry Lefroy presided. In response to the toast "Our Distinguished Guests," coupling the names of Lieuts. Greely and Ray and Mrs. Greely, Lieut. Greely said:

"_Mr. President, Ladies and Gentlemen_: I need scarcely say that this flattering reception from representative men of one of England's most distinguished societies touches deeply my feelings as a soldier and as a man. It is not alone that you represent the science and learning of England and the world, but that you are all countrymen of those daring seamen and explorers whose names and whose deeds have become household words throughout the world. Hudson, Baffin, Cook, Nelson, Parry, Franklin, and a score of others among the dead; McClintock, Nares, and Markham, and last, but not least, the man whose name was oftenest on our lips when praying for relief during the past terrible winter--Bedford Pim. What those men have done the whole world knows. That you should deem aught that I have done worthy to placed with the deeds of those illustrious men must always be a source of pride to me. For three centuries England maintained against the world the honors of the farthest north. Step by step every advance was made by Englishmen. Now England's grandest colony presses to the front; but none the less is the honor England's, for at the price of her sons' lives and by their toil the path was cleared. But for Beaumont's dauntless pluck and indomitable energy in 1876, Lockwood would never had made his great northing in 1882. I have during a quarter of a century's service, as becomes a soldier, been jealous of my honor. I have striven to maintain it in the field, fighting and bleeding for my country, and at my desk studying and discussing scientific data; in the Arctic Circle, when pursuing scientific and geographical work, or later, when stranded by adverse fate, and starving and freezing upon the barren coast. This marked and public testimonial of your approval cannot fail to make me doubly jealous of it in days to come."

Lieut. Ray followed, returning thanks in his own behalf.

After other speeches Sir Henry Lefroy presented Lieutenant Greely with the following informal address:

"Montreal, Sept. 2, 1884.

"The undersigned, on behalf of many warm friends and admirers, and as representing various professional and scientific pursuits, desire to express to you their appreciation of the courage and devotion which has characterized your conduct during the trying circumstances of your late Arctic service. We trust that your health may soon be restored, and that you may long be spared to tender, as during your past distinguished career, those valuable and distinguished services to your great country which have already placed you among the foremost of scientific explorers of the age.

"Yours faithfully, Rayleigh, President."

In introducing Lieut. Greely, Sir Henry Lefroy, referring to the persistence of purpose shown by his party in bringing back the pendulum apparatus, remarked that there was nothing nobler in the annals of scientific heroism than the determination of these hungry men to drag the cumbersome box along their weary way.

It was fully two minutes after rising before Lieut. Greely could speak, so great was the outburst of enthusiasm which greeted him. He remarked that he was surprised to learn that the ground did not thaw lower at Lieut. Ray's station, which was ten degrees farther south than his own, where the ground thawed to a much greater depth--namely, twenty to thirty feet. In regard to an open polar sea, he differed from Lieut. Ray. He did not believe there was a navigable sea at the pole, but he was of the opinion that there was open water somewhere about.

The geographical work of the Lady Franklin Bay expedition covers nearly three degrees of latitude and over forty degrees of longitude. Starting from latitude 81 deg. 44 min. and longitude 84 deg. 45 min., Lieut. Lockwood reached, May 18, 1882, on the north coast of Greenland, latitude 83 deg. 24 min. and longitude 40 deg. 46 min. From the same starting point he reached to the southwest, in May, 1883, Greely Fiord, an inlet of the Western Polar Ocean, latitude 80 deg. 48 min. and longitude 78 deg. 26 min. This journey to the northward resulted in the addition to our charts of a new coast line of nearly 100 miles beyond the farthest point seen by Lieut. Beaumont, R.N. It also carried Greenland over 400 miles northward, giving that continent a much greater extension in that direction than it had generally been credited with.

In a subsequent speech he took occasion to say that a fact had surprised him. It was the discovery that when the tide was flowing from the North Pole it was found by his observations that the water was warmer than when flowing in the opposite direction. He took the trouble to have prepared an elaborate set of observations showing this wonderful phenomenon, which would eventually be published. To him these pecularities were unexplainable, and be hoped that the observations would be studied by his hearers, and some explanation found in regard to the thermometric observations of the expedition. He remarked that the mean temperature for the year of the hourly observations was 5 degrees below zero, which justified him in saying his station was the coldest point of earth ever reached.

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DIAMOND MINING IN BRAZIL.

It was in 1729 that the Portuguese government learned of the discovery of the diamond that had been made in the rivers of the environs of Diamantina by some adventurers who had entered this region in search of gold. Since that epoch the exploitation of this gem, pursued under varied regimes, and with diverse success, has never ceased. As soon as it heard of this discovery, the Portuguese government thought it would make as much profit out of it as possible, so it no longer authorized any other exploitation in the Diamantina regions than that of the diamond, and it imposed upon such exploitation a tax that was fixed at 28 francs per laborer in 1729 and 224 in 1734. From 1734 to 1739 all operations were suspended, and a more lucrative organization for the treasury was sought for. In 1739 the era of contracts was inaugurated. The exploitation of the diamond was farmed out for four years to a _contratador_, who was to work a certain territory with a number of men, fixed at 600 as a maximum, and to pay into the treasury a sum per workman (whether working or not) that varied from 1,288 francs per year in 1734 to 1,344 francs for the last contract, that ended in 1772. At this epoch the government took the exploitation of the diamond in hand, and gave it in charge of a special administration, which was submitted to the direction of the treasury of Lisbon, and which had at its head a comptroller. This new regime lasted till 1845. In order to render the surveillance of the treasury agents efficient, and prevent smuggling (which can be so easily done with an object like the diamond), it was necessary to impose a special regime over the entire region of Diamantina, and, in fact, the latter was, up to the independence of Brazil, submitted to Draconian regulations.

We only know the quantity of stones that were discovered during the period when operations were directed by the Royale Extraccao, from 1772 to 1845, and this was 269,870 grammes, or more than 1,300,000 carats. It should be understood that what was taken by stealth does not enter into this total, and it must be stated that during the latter years, when the Extraccao existed only in name, smuggling must have been active.