4

WYLAM'S PATENT IMPROVEMENTS IN HYDRAULIC PRESSES.

which opens into the discharge or return pipe K; N1 N2, are two plainstemmed piston valves, which work freely up and down in the chambers M1 M2, through leathern collars and stuffing boxes S S, and open and close the different ports according to the different positions they are made to assume; O, is a double-ended hand lever, which is connected to the tops of the stems of the two piston valves, and turns on a pin or fulcrum, supported by the standards PP, by the movement of which lever to and fro, the piston valves are alternately raised and lowered. The chamber M2, which contains the port T, leading to the return or discharge pipe K, is of larger capacity than the chamber M1, and the piston valve N2 which works in it is of a correspondingly larger size than the valve N1 of the chamber M'; and these larger dimensions are given to the chamber M2, and the piston valve N2, in order the better to facilitate the discharge of the water. But by enlarging the stem of the lesser piston valve N1, at the bottom end, from m to n, (as shown in fig. 8,) and thus increasing the surface exposed to the pressure of the injected water, a perfect balance is established between the two piston valves. In fact, so complete is the equipoise between the two piston valves when they are thus constructed, (that is to say, when they are constructed according to the relative proportions represented in fig. 8,) that the lever is turned by hand with the greatest ease, equally to the one side or the other. The chamber M2, and piston valve N2, moreover, made considerably longer than the chamber M1, and piston valve N', and the difference in length is so adjusted that the piston valve N2, shall quite close the eduction port T, before the piston valve N1 can rise so high as to throw open the induction port R1. Again, the piston valves are bevelled off at their lower extremities, as shown in the figures, and these ends fit into seats w1 w2, made to fit them exactly in the chambers M1 M2. By these combined means the whole water which enters the valvular governor is constantly either being forced into the press cylinder or being discharged back into the supply cistern, and but little, if any of it, runs to waste.

are,

The mode of working the press, and

of the machinery connected therewith, is as follows:-The safety-valve V of the pumps (which acts of course equally as a safety-valve to the reservoir communicating with them,) is first loaded according to any degree of pressure desired to be transmitted to the press, and the pumps then set to work. When the whole of the water in the supply cistern H has been pumped into the reservoir, the air cocks, q qq, attached to the suction pipes, are opened, and the pumps continued to be worked, and air instead of water thereby thrown into the reservoir, until the safety-valve begins to rise, which is an evidence of the reservoir being in a fully charged state. The water-induction port is then opened by means of the double-ended lever O, on which the water is impelled with great force and rapidity up against the piston or follower of the press, owing partly to the elastic force of the air in the top of the reservoir acting on the water, and partly to the gravitation of the water itself, (the reservoir rising above the level of the cylinder of the press.) The instant the piston has performed its stroke, the lever O, is reversed, and the eduction port T, opened; and as soon as the first charge of water has passed away, the induction port is re-opened for a second charge, and so on through any number of charges and discharges. The pumps in the mean while continue working unintermittingly, returning the water back to the reservoir as fast as it comes from the press, and injecting along with it a portion of air, more or less, which makes up for any absorption of the air by the water in the reservoir, and thus keeps the reservoir in a state of constant efficiency. When the air seems from the action of the press to be injected in excess, it is only necessary to close more or less the air cocks, q q q. Each press must of course have a separate valvular governor, and separate sets of induction and eduction pipes, and a separate person to work it; but the number of presses which may be worked on this system by one set of pumps and one reservoir, is only limited by the respective capacities of the pumps and reservoir. In the figures, six presses are supposed to be worked by three pumps and one reservoir, but these are merely given as relative numbers, which are found convenient in practice. Instead also of dis

EMPLOYMENT OF TURF OR PEAT AS FUEL FOR STEAM ENGINES.

tributing the power furnished by the reservoir over a number of presses, it may, if preferred, be concentrated on one. The lever O, too, may be worked with any degree of rapidity required, so that either a great pressure sustained through a considerable length of time, or a smaller pressure sustained during a shorter space, is equally attainable.

EMPLOYMENT OF TURF OR PEAT AS FUEL
FOR STEAM-ENGINES.

[From a paper on the "Artificial Preparation of Turf." By Robert Mallet, Esq., C. E., communicated to the Institution of Civil Engineers of Ireland.]

The most exaggerated statements have been made by some authorities, upon which reliance is placed, as to the evaporative power of turf, and hence of its value as fuel. "One pound of pure dry turf will evaporate six pounds of water,' Doctor Kane says (Indus. Resources, p. 35,) on the authority of Peclet. However possible this may be, in experimenting with calorimetrical apparatus, certain it is, that the results of the most

careful practice on the large scale fal immeasurably below it.

5

The City of Dublin Company's steam ers on the Shannon are not "exclusively worked with turf." It is found impossible to keep up steam, especially in bad weather, without an admixture of coal; but I have been enabled, by a discussion of both fuels consumed in given times and distances, to arrive at this resultthat it requires 51 lbs. of turf, of the best quality and dry, to boil off one cubic foot of water into steam, on the average; and that under the boilers of those vessels about 8 lbs. of good South Wales steam coal are equivalent to 48 lbs. of turf; so that, for equal weights, the turf is worth one-sixth of the coal. These results were obtained by me in the course of an inquiry, having in view the working of steam-boat boilers, on the locomotive construction, with turf, upon canals in Ireland. Experiments were made with care, in working with good dry turf, a locomotive boiler having the following dimensions:

Fire-box, 3 ft. 3 wide by 3 ft. 4 deep by 2 ft. long.
Grate, 3 ft. 3 by 2 ft. =6 square feet.

Tubes, 54 tubes-2 in. diam. 6 ft. 9 long.
Surface exposed in fire-box
Surface exposed in tubes

40.89 square feet. =240.04 square feet.

Total heating surface......280.93 square feet.

When this boiler fully supplied its engines with steam, at 60 lbs. pressure above the atmosphere, it consumed 114 lbs. of gas coke, in evaporating the same volume of water as was done by 868 lbs. of dry turf. This gives the value of turf to coke in this boiler in the ratio of 1:7·61, which is below that given in the boilers above alluded to on the Shannon.

The consumption was so rapid in the locomotive boiler that it was almost impossible to supply the fire, and maintain the draught.

The consumption of good dry turf, under a long cylindrical boiler, supplying a ten-horse high pressure engine, used in pumping water, and well set and arranged, erected under my own direction, was, on the average, 54 lbs. of turf for each cubic foot of water evaporated into steam, at 30 lbs. pressure, per square inch, above the atmosphere.

In a twenty-horse power condensing engine, erected under my direction, (by our firm,) with wagon boilers, which

were already in existence, the consumption of tolerably good turf averaged from 57 lbs. to 60 lbs. for each cubic foot of water, evaporated into steam, of about 5 lbs. pressure above the atmosphere.

of

In a thirty-five horse power condensing engine, (Sheane and Beale's, Mountmellick,) the largest I have found worked with turf in Ireland, I found, last year, the consumption varied from 55 to as as high as 80 lbs. of turf to the cubic water, evaporated into steam, at about 7 lbs. above the atmospheric pressure. The boilers are well set, and the furnaces well calculated for burning turf, which, however, was not quite dry, (even to the hand,) and only moderately good in quality. Coal at 16s. per ton would have been quite as cheap; and if the turf were a little more damp, as in the winter time it would be, coal would be the cheaper fuel. If the turf had been quite dry, on the contrary, I calculated that the saving by its use, in place of coal at 16s. per ton, would amount to about 6s. per day, of twelve hours.

ON THE DETERMINATION OF THE MELTING POINTS OF METALS, ETC.

ON THE DETERMINATION OF THE MELTING POINTS OF METALS, ETC. 7

and these experiments appeared satisfactorily to warrant the assumption that alloys of silver and gold, and gold and platinum, have melting points proportional to the melting points of each of these metals; an assumption made by Prinsep.

Mitscherlich's determination of 1560° C. as the melting point of platinum was referred to, but as this involves all previous determinations of the melting points of other metals being erroneous, that is, much too high, Plattner was justified in assuming his own determination as the basis of the temperature given in Table II. and in his further researches.

The melting points of-
Lead being taken at

Silver

Gold

Platinum

334° C. 1023° C.

1102° C.

2534° C.

it was easy, according to the method described, to determine the melting points of the most refractory substances, so long as these were under that of platinum. The alloy being found having the same melting point as that of the body under research, its value was then

x =

A s + B s'
100

Where A and B are the weights, and s and s' the melting points of the metals contained in the alloys. And 100 parts by weight of alloy, and body under experiment, were taken respectively.

Attention was called to the circumstance that Daniell had fixed the melting point of copper at 1091° C., or under that of gold. Prinsep found, from constant experience as an assayer, that this is not the case, and fixed the melting point to be the same as that of an alloy of 97 parts of gold and 3 parts platinum. Plattner found 95 parts gold and 5 platinum to answer more exactly, and hence, applying the above formula, 95 x 1102° + 5 x 2534° 100

x=

the melting point of copper.

=1173°

The second part of Plattner's researches on the Determination of the Temperature necessary for the Formation of different Silicates, was promised, should the society consider it of sufficient interest, as the subject of a future communication.

TABLE I.

Tabular view of the Melting Points of Metals, as determined by different Experiments.

ON THE MEASURE OF IMPACT, BY PRESSURE OR WEIGHT. BY PROFESSOR L. GORDON.

MAGNETISM.-ANOTHER IMPORTANT DISCOVERY.

The phenomena of magnetism have been attracting the attention of scientific men for some time past; and it appears, from the results of their investigations, as if we were advancing to a knowledge of many of the more secret operations of nature. interesting discovery has been recently made