which directs its passage down the shaft, is the object sought in all safety cages. The author's plan for effecting this is a mere adaptation of an instrument well known to miners-the key or wrench used for raising and lowering the boring rods. It has never been known to lose its hold, and the greater the strain the firmer is its gripe. To adapt this instrument to the cage, a slight modification of the upper shoes or slides is all that is necessary. These shoes or slides are, as usual, two in number, and placed on opposite sides of the cage and in opposite directions. Each of them has a single bolt or stud by which it is attached to the cage, and around which it turns, a long arm to the extremity of which the winding-chain is attached, a stop which prevents the arm from being pulled above the horizontal line, and a spring which lowers it when the winding-chain is slack. The author illustrated the various parts by diagrams and a working model.

On Harbours of Refuge. By DONALD BAIN.

On a Boat-lowering Apparatus. By A. BALTEN.

On an Artesian Well in the New Red Sandstone at the Wolverhampton Waterworks. By J. F. BATEMAN, C.E., F.R.G.S., F.G.S.

The town of Wolverhampton has been, up to a recent period, supplied with water produced by two deep shafts, one sunk about 300 feet deep into the lower new red or Permian measures, and the other to a somewhat similar depth in the new red sandstone proper. From both of these wells a large quantity of water was anticipated by the engineer who advised their construction, but their yield is under 200,000 gallons a day each, the water being pumped, in one case, from a depth of about 180 feet, and in the other 246 feet.

The quantity thus yielded being insufficient for the supply of the district, new works have been constructed, which I have just completed, for bringing water from the river Worth at Cosford Bridge, about nine miles from Wolverhampton, and three from Shiffnall in the county of Salop.

The works are constructed for the supply of 2,000,000 gallons per day, and the water has to be forced to a height of 500 feet for the supply of the town.

The river Worth, at the place at which the pumping works are constructed, is not more than 40 or 50 feet above the Severn, which it joins at Bridgenorth, about eight or ten miles distant. It may therefore be considered to be at the bottom of a basin a little elevated above the sea. From the character of the surrounding hills, and the inclination of the beds of the new red sandstone, it appeared to me very likely that, although the wells which had previously been sunk on the high plateau of Wolverhampton had proved comparative failures, a considerable quantity of water might be found in the sandstone at Cosford Bridge, and that possibly some might rise to the surface and flow as an artesian well. I therefore obtained the sanction of the Directors of the Company to sink a bore-hole for the purpose of ascertaining the fact. In some parts of the country, as in Cheshire and Lancashire, on the shores of the Mersey, the new red sandstone is very clearly divided into four distinct portions, consisting of an upper hard mass, about 300 or 400 feet thick, a soft mass, about the same thickness, a second hard mass, and a lower soft mass,-all of pretty much the same thickness. In the neighbourhood of Wolverhampton and Shiffnall these distinctions are not so clearly exhibited; but I had reason to believe, from the position of the works, that a bore-hole, of about 200 feet in depth, would pierce the hard rock on which they were situated, and reach the soft rock beneath.

The bore-hole was commenced 12 inches in diameter, and continued at that size for 70 feet in depth, when it was diminished to 7 inches, and continued for 190 feet, making a total depth from the surface of 260 feet.

The first water was met with at a depth of 22 feet 4 inches, and from that time it rose to the surface and flowed over as an artesian spring, constantly increasing in quantity as the depth increased, till the boring was discontinued; at which time it amounted to about 210,000 gallons per day.

The following Table will show the manner in which the water increased :

Throughout the whole depth of boring the rock varied little in character: it was nearly all hard rock; sometimes very hard, with occasional beds of softer stone. For the last 40 feet or so the soft beds were thicker, but otherwise there was little change from top to bottom.

The greatest increase of water took place at 214 feet and 227 in depth, at each of which depths there was an increase of 20,000 gallons per day. The soft rock I anticipated was not met with at the depth I expected, but sufficient was done to prove the abundance of water. A larger bore-hole, which would permit the ascent of a larger column of water, would materially increase the produce as an artesian well; while a shaft sunk 30 feet or 40 feet deep, and exhausted to that depth by pumping, would yield a very considerable quantity. As the whole rock is charged with water to the level of the river which forms its natural outlet, and as the boring shows that the lower beds receive their supplies from distant sources, the supply to be obtained may reasonably be expected to be inexhaustible, within the limits of that which is due to the percolation of the rain upon the collecting area.

Description of the Glasgow Waterworks, with Photographic Illustrations taken at various stages of the work. By J. F. BATEMAN, C.E., F.R.G.S., F.G.S.

On Coal-burning without Smoke, by the method of Steam-Inducted Aircurrents applied to the Locomotive Engines of the Great North of Scotland Railway. By D. K. CLARK, C.E.

The whole apparatus is external to the fire-box, and therefore not exposed to heat, and it is controlled in the most perfect manner by a single stopcock. Air is admitted above the fuel by one or more rows of tubes inserted through the walls of the fire-box, and jets of steam are projected through the air-tubes from nozzles th of an inch diameter, in small steam pipes, placed outside the fire-box, to increase the quantity and force of the air admitted above the fuel, in order to consume the smoke. The jets of steam are used principally when the engine is standing, with the aid of a light draught from a ring-jet in the chimney, to carry off the products of combustion; and they may be shut off when not required. The supply of air through the tube may also be regulated by dampers.

The grate-bars are placed close together, with narrow air spaces, and the ash-pan and damper are tightly fitted. The level of the fuel should at all times be below the air-tubes. By the adoption of this method it requires a less weight of coal than the engines formerly required of coke for the same duty, and thus saves more than the whole difference in price of the two fuels.

Description of a Patent Pan for Evaporating Saccharine Solutions and other Liquids at a temperature below 180° Fahr. By RICHARD Davis, F.S.A., F.L.S.

This consists of a cast iron, copper, or other pan, through which is inserted a series of copper tubes, similar to those used in a locomotive boiler. On each side of the

pan, to which the tubes are riveted, is a cast-iron steam chest, with stops, to ensure a circulation of the steam through the tubes in a serpentine manner. Between these tubes a series of copper discs is made to revolve, the diameter of which is 3 feet, and the thickness about th of an inch.

The condensed water from the tubes, caused by the evaporation of the liquid in the pan, is received in an ordinary condensing box, fitted with a ball and valve, and is thence conveyed to a receiver, ready for readmission to the boiler at a temperature of 160° or 170° Fahr., according to that of the liquid under evaporation.

This method affords the means of evaporating syrups and other liquids at a temperature under 180°, at which temperature sugar will not carbonize.

The economy of fuel in this process is very great, while evaporation is as rapid as when the vacuum pan is employed. The cost of the latter (the method of working it requiring skilled labour of a superior degree) is such, as to place it out of the reach of most proprietors in the colonies, whilst the cost of this pan is trifling, and may be worked by an ordinary boiler-man. For the revolutions of the discs little power is required, as they are supported upon centre bearings, and may be turned by manual or any other motive power.

Every part of the machinery is open to view, and from its extreme simplicity can be cleaned, or any accidental injury repaired by a common workman. One great advantage to be derived from the use of this apparatus is the facility it affords for working up molasses, and thus converting the second product into an article almost equal to that of the first.

On the Engines of the 'Callao,' 'Lima,' and 'Bogota. By J. ELDer.

In these engines the steam enters at 42 lbs., and is expanded to nine times, or to 43 lbs., namely, from 42 lbs. to 14 lbs. in the small cylinder; it then enters the large cylinder at 14 lbs., and is expanded to 43 lbs. ; but as the second piston is three times the size of the first, the gross load will be the same on both pistons, and the piston rods, crossheads, and connecting rods may be duplicates of each other.

From the above pressures of steam at the entering of the cylinder, it is evident that, unless the inside surface of the large cylinder is retained about 210°, condensation of the steam on entering is certain, and such condensation will chiefly evaporatė into the condenser while the eduction port is open, and the latent heat necessary to evaporate such condensation will be much greater than what would have radiated from the hot cylinder to the condenser, had no condensation taken place; and such heat would be entirely lost. In the same manner it might be mentioned, that the inside surface of the small cylinder should be retained as high in temperature as the steam that enters it; and in order to attain this object, every effort should be made in the construction of steam machinery. It is evident, that, for the small cylinder, superheated steam is absolutely necessary for this purpose, either in the jackets or cylinder; and in the large cylinder the temperature of steam direct from the boiler to the cylinder may be sufficient, if communicated through a pipe or aperture large enough.

In the engines under description, the pipe supplying steam to the jackets was 2 in. diameter, and the steam was superheated to upwards of 400 degrees that entered the jacket. It was found that a large supply to the jacket saved a vast quan. tity of heat, which can only be explained by the principles above mentioned, namely that any quantity of heat supplied to the jackets assisted in proportion to the quantity of latent heat it saved being evaporated to the condenser during the eduction of the steam; and if the pipes to the jackets were large enough, or sufficient to prevent the condensation referred to, the economy of the machinery was realized to the greatest extent.

The writer begs to call the attention of all parties concerned, to the performance of Cornish pumping-engines, and more particularly to the similarity of action of the steam-jacket in these engines to the principle of that of the double-cylinder engine with steam-jackets. In the Cornish engine the piston is single-acting, and the jacket has twice the time to do its work, or rather the steam in the cylinder is twice the time in contact with the jackets that it is generally with Watts' engine; so that the Cornish engines have very large jacket surfaces in proportion to the power deve

loped. With these features in view, the engineers constructed the engines now under discussion, and to this cause may be attributed a considerable portion of their success, and to the non-observance of these features the almost total failure of economy in the expansive working of most steam-engines on board of steam-ships, namely, by constructing large engines, going slow, without steam jackets, or superheating of steam: such engines would, of course, present a most favourable opportunity for improvement by adding any mode of superheating apparatus.

From the foregoing it is also conclusive, that with the ordinary construction of steam-engines afloat, small engines going fast would consume less coal per indicated horse-power than large engines going slow; but with engines such as those of the 'Callao,' 'Bogota,' and 'Lima' the converse will be the case, carried, of course, within moderate limits.

In reversing the engines, the eccentrics are made to overrun the engines by a donkey-engine till they arrive at the backing position, a plan which is less likely to cause accident than the ordinary methods. This donkey-engine has been found to be most satisfactory in its application.

The boilers are tubular, two in number, with iron tubes.

Each boiler has three furnaces, 3 feet 4 inches wide, and 63 feet long, or making an aggregate of 130 square feet of fire-grate.

The tubes are of iron, 288 in number, 4 inches inside diameter, and 6 feet long. Each vessel has an oval steam-chest, 12 feet high and 8 feet long, and 5 feet broad, with three uptakes through this steam-chest, each 2 feet diameter and 15 feet long. This makes a strong form of takeup where it joins the tube plate, especially in boilers firing across the ship; the feed-pipe of the boilers enters into a long flat tank or shield in front of the furnaces in which the furnace-doors are formed. This shield forms a protection to the firemen from heat, and makes the heat, otherwise lost, available for the feed water. In the 'Callao' there is a third coil of feed-pipe in the funnel, to heat the feed water. Such then are the leading features of this machinery, and the results are as follows:

This plan of the boilers gave steam to the engines superheated to about 400 degrees by the uptakes, showing that the various systems of superheating are unnecessarily complicated; indeed, in the ‘Lima,' the steam got so far above 400 degrees, that in the 'Bogota' the steam-chests were made 2 feet lower, and two small feed-pipes were made to feed the boiler when too much superheated by a tap in the steam-chest. The superheated steam, though upwards of 400 degrees of heat, was found quite inadequate to prevent condensation in the cylinder, without the steam-jacket cock being fully open.

The writer begs to draw attention to the fact, as in the case of double-cylinder engines it is so prominently observed, by comparing the respective diagrams of the low- and high-pressed cylinders, especially as in those engines the cylinders are so close that the diagram of one is an exact counterpart of the other, when there is no condensation; and it is somewhat curious to observe, while taking diagrams of the low-pressed cylinder, the gradual development of the diagram, with the jacket-cock fully open, compared with that when it is shut.

When the steam was at a pressure of 21 lbs. above the atmosphere, the temperature at the surface of the water was 264 degrees, and at the top of the steam chest 400 degrees Fahr., showing that the steam was surcharged to the extent of 136 degrees, notwithstanding that the steam was in direct and unimpeded contact with the surface of the water. The engines made during the trial trips, which were generally half a day in length, from about 23 to 26 revolutions, and indicated from 1000 to 1300 horse-power during that time, and consumed from 20 to 25 cwt. per hour, with the surface-blow-off cocks open. The Callao,' 'Lima,' and 'Bogota have all shown a consumption of from 2 to 23 lbs. per indicated horse-power per hour best Welsh coals, and the speed of the ships from 12 to 13 knots per hour.

The steam-ship 'Callao' has now been plying between Valparaiso and Panama with Her Majesty's mails, for upwards of nine months, and has performed her work in a most satisfactory manner. The distance between these ports is upwards of 3200 miles, and this she performs regularly on about 300 tons of coals. The 'Callao' made the run from Liverpool to Valparaiso in, I think, about 36 days steaming time, which averages about 240 miles per day during a run of 9000 miles,

on a consumption of about 20 cwt. per hour. The 'Lima' has also arrived at her destination, after a most successful run; she performed the distance of 1500 miles, from Valparaiso to Callao, in 141 hours, consuming 150 tons of coals, logging at an average of 260 miles per day during that distance, considerably faster than she had ever done with her original engines, and on less than half the coals consumed. The 'Bogota' was completed and tested on the 1st of September last, and found fully equal to the others. She made the run from the Cloch Light in the Clyde to the Bell Buoy at Liverpool in 15 hours, against a strong head wind, and consumed during that distance 15 tons of Scotch coals.

At the Admiralty trial, which took place immediately on her arrival at Liverpool, she averaged upwards of 13 knots, the engine made 25 revolutions; she indicated 1080 horse-power, and consumed about 21 cwt. per hour of Scotch coals; the steam was superheated to 340 degrees on entering the cylinder, and the thermometer at the water-level of the boiler showed 264; the pressure in the boilers was 27 lbs., and the vacuum in the condensers 26 inches. She left Liverpool for Valparaiso on the 11th of the present month, with sufficient coals to carry her 5000 miles, at 240 miles per day, and a full complement of stores for the passengers on board; her draught of water on leaving Liverpool at the load line was, aft, 14 ft. 6 in.; forward, 13 ft. 9 in.; and displacement, 1700 tons. She steamed to the Holyhead Light, where the pilot left her, at the rate of 113 nautical miles per hour against a strong head wind; the engines were making 20 revolutions; the steam pressure was 26 lbs. ; the vacuum 26 inches; and the consumption of coals 22 cwt. best Welsh coals per hour.

The engineers are now constructing the machinery for three other steam-ships on this principle, with boilers on the cellular cylindrical spiral principle. In conclusion, the form of engines now described gives regularity of motion while working expansively to the fullest extent, the expansion principle is fully realized, and the engines are of a strong architectural figure, with the various parts easily got at, and reduced to simple forms, and present every facility for reversing freely by the engine-driver.

Experimental Researches to determine the Density of Steam at various Temperatures. By WILLIAM FAIRBAIRN, LL.D., F.R.S., and THOMAS TATE.

For a perfect gas, the law which regulates the relation between temperature and volume is known by Gay-Lussac's or Dalton's law, and is expressed by the equation v XP_459+t,

=

(1)

Steam at the temperature of 212° has a density such that its volume is 1670 times that of the water which produced it; substituting these values of volume, temperature, and pressure, we get for the volume of steam from a unit of water at any other temperature,

V-1670X 15459+t
670

.X

or V 3711
=

Р

459+t
P

(2)

These are the well-known and received formulæ from which all the tables of the density of steam have hitherto been deduced, and on which calculations on the duty of steam-engines have been founded. They have not, however, up to the present time been verified by direct experiment; various speculations and theories have from time to time been propounded, as giving more accurately the density required, which, however, need the evidence and verification of direct experiment.

Great difficulties have hitherto stood in the way of making direct experiments. The temperature of saturation, or temperature at which the whole of the moisture is converted into steam, whilst no part of the steam is superheated, must be determined with the utmost accuracy, or the results are of no value.

The difficulties thus resolve themselves into finding some test of sufficient accuracy and delicacy to determine the point of saturation. This has been overcome by what may be termed the saturation gauge; and it is in this that the novelty of the present experiments consists.