322 



THE CIVIL ENGINEER AND ARCHITECTS JOURNAL. 



[September, 



depths of water in tlie two compartments. He thought Mr. Mackain was 

 entitled to much credit. 



Coradino Tank at Malta. 



A drawing of the Coradino Tank, erected in 1S41-2, in the island of 

 Malta, was presented by William Lamb Arrowsmith, Assoc. C.E. (Superin- 

 tendent of Government Works at Malta). 



It was described as the largest modern covered tank in Europe, its cubic 

 contents being 700,000 feet, and with its settling reservoir it would contain 

 15,000 tons of water ; the roof was supported by rows of square pillars 15 ft. 

 in height. It was intended to form a part of the works for supplying the 

 island with water, a description of which was promised to the Institution to 

 complete the paper on the supplies of water for cities, the first part of which 

 has alrcadv been received. 



Artesian Wells. 



A letter was read from the late Sir John Robison, giving a short account 

 of the Artesian Well at t/ie Abbaioire (I? Crenelle, Paris. 



The Ahbatoire being at too high a level lo obtain an adequate supply of 

 water by the ordinary means, it was proposed, about eight years since, to 

 sink an artesian well within the premises, which proposal having been agreed 

 to, the execution of it was intrusted to Monsieur Mulot. The work liaving 

 been pcrseveringly carried forward through many difficulties, the boring was 

 terminated by the auger penetrating the water-bearing strata on the 2Cth 

 February, 1841, when a sudden and violent rush of water occurred, overflow- 

 ing at the surface of the ground. As the boring progressed, tubes of rolled 

 iron, and subsequently of copper, were inserted to support the sides, the first 

 being 12.; inches diameter, and the lowest about 6j inches diameter, reaching 

 to a depth of 179-1.' English feet. The quantity of water thrown up while 

 the bore remained in this state was about 880,000 imperial gallons per day, 

 at a temperature of 824° Fahrenheit ; the expense incurred up to this time 

 being upwards of £12,000 sterling. Sir John examined the theoretical rea- 

 sons which had been given for the contortion of the tubes, which had been 

 attributed to violent pulsations in the flowing water acting upon the I 

 of them, crushing them inwards ; he objected to this reasoning as not being 

 in accordance with the laws of hydrostatic pressure, and attributing it rather 

 to mechanical causes arising from the force used in forcing the tubes down 

 the hole, and even more to the violence they were subjected to in being 

 withdrawn from it. 



The letter was illustrated by a lithographic section of the well, which was 

 presented by William Cubitt, Assoc. C.E. 



Remarts, — Mr. Cubitt had recently visited the well, and found the water 

 flowing with considerable force through an orifice in the vertical pipe about 

 ;s feet beneath the level of the ground; the nozzle of the orifice, which was 

 10 inches diameter, was about half filled, and the stream was reported to be 

 supplying about 2500 litres (S50 gallons) per minute, at a temperature of 

 82° Fah. The water was not clear; it deposited a considerable quantity of 

 fine sand, and occasionally stones of about 2 inches cube were brought up. 

 lie was informed that the water bad at one period ascended to between 70 

 and 90 feet higher than the ground. 



Mr. Taylor observed, that the temperature of the water nearly coincided 

 with that of the United Mines in Cornwall, which were 295 fathoms, or 

 1770 feet deep. The highest temperature recorded there was, he believed, 

 96 : ' Fah. It. was well ascertained now, by the experiments of Mr. Pox, that 



the beat was not increased either by the decomposition of the pyrites, or the 

 number of men ami horses employed in the mines. 



Mr. F.nys said, that the experiments by Mr. Fox, as published in the re- 

 port of the seventh meeting of the British Association (vol. vi, p. 133) gave 

 a temperature of 92 in the lode at a depth of 290 fathoms, where it was first 

 reached in the cross-cut; but on proceeding along the same cross-cut, at 

 10 fathoms from the lode, the temperature decreased to 86° 3', and at 24 

 fathoms distant it was 85° 3'i this would give a close approximation to the 

 temperature quoted by Mr. Cubitt. 



Mr. Braithwaite inquired at what depth the temperature began to increase; 

 landsprings were generally at about 52°, and be found the water in wells 

 600 feet deep usually at 53° or 54°. He bail understood that the tempera- 

 ture increased 1° for every 65 feet, after a certain depth. 



Mr. Enys said, that Mr. Fox's experiments gave a ratio of increase of 1° of 

 temperature in IS feet, calculated from the surface. He thought that the 

 close approximation of the temperature of the land-springs, and that in the 

 wells mentioned by Mr. Braithwaite, might be accounted for by the rapidity 

 with which the water filtered through the strata of the Loudon basin. 



Mr. Taylor agreed that the heat of the water was influenced by the nature 

 of the strata; the Cornish miners, when they were taken to the North Welsh 

 mines, were much inconvenienced by the coldness of the water in the latter, 

 although the depth of the mines in both districts was nearly identical. 



Mr. Braithwaite believed that his view of the temperature of wells would 

 he corroborated by the coldness of the water in the new well at Southamp- 

 ton, which had now arrived at a very considerable depth, and he understood 

 that the temperature of the water was about 54°, 



Mr. Simpson said, that the well at Southampton had been sunk and bored 

 to the depth of 1063 feet ; the supply of water was not considerable, and he 

 was not aware that any observations had been made as to the temperature. 

 A well at Chichester had now arrived at the depth of 1013 feet, and was still 

 being carried lower. 



Mr. Sopwith contended for the accuracy of the investigations of Count 

 Brenner on the temperature of two German mines, and of Messrs. Fox - , 

 Buddie, and others in England; the differences between the results obtained 

 were so trifling as to induce confidence in the conclusion they bad arrived 

 at, which was, that after allowing for the radiation of beat at a certain dis- 

 tance from the surface, the temperature increased 1° for every 50 feet in 

 depth. This law might not hold good in certain local basins, where from the 

 nature of the strata the percolation of surface water was rapid, hut in the 

 extensive mining districts it certainly was correct. 



Mr. Cubitt suggested that the close approximation of the temperature of 

 the water in the well at Paris and that observed by Mr. Fox at the same 

 depth in Cornwall, might arise in some measure from the large volume of 

 water in the former, and the rapidity with which it arrived at the surface : 

 whereas in the deep wells which hail been mentioned, the water had probably 

 been allowed to cool before the temperature bad been ascertained. 



Mr. Clarke corroborated the opinion entertained by Mr. Cubitt ; in a well 

 which lie had sunk to the depth of 540 feet at St. Alhan's, he obtained, by 

 an apparatus constructed for the purpose, some water from the bottom of 

 the well, and found it 4° hotter than that which was pumped up from the 

 same well. At the bottom of a well at Messrs. Barclay's brewery, 367 feet 

 deep, the water was 3° hotter than at the water-level in the same well. 

 Local causes frequently affected the temperature of water in wells; be had 

 seen instances of the water being warmer at 60 and 70 feet deep than at 

 300 feet, but these cases would not influence the general law. 



Mr. Viguolcs considered the facts mentioned by Mr. Clarke to be very 

 valuable, and as bearing out Mr. t'ubitt's idea; there could be little doubt 

 that if, by means of self-registering thermometers, the temperature of the 

 water was ascertained, at the issue of the springs, at the bottom of deep wells 

 which were not influenced by local causes, the result would prove in accord- 

 ance with the observations of Fox and others. By the laws of the circu- 

 lation of fluids the heavier water, which bail been cooled at the surface, 

 mingled with the lighter and wanner water as il rose; the sides of the well 

 also tended to abstract the heat; therefore the temperature should he ob- 

 tained at the greatest depth in order to make any correct experiment. 



Mr. Braithwaite agreed in the influence of local circumstances ; in a well 

 at (heshiiiii. :il a depth of 40 feet, a sulphureous spring issued, the vapour 

 of which almost killed the workmen: and when at last it was built out, the 

 bricks continued so hot that the band could scarcely be borne against them. 

 Below that point very cold water was met with. 



April 11. — Joshua Field, V.P., in the Chair. 

 Tin; Water-pressure Engine at FnEvnuRn, Saxony. 

 Description. By William Lewis Baker, Grad. Inst. C.E. 



The machine described in this communication was designed by Herrn 

 Brendel in 1823, and constructed in 1824, for draining the " Alte Mordgrube" 

 mine, one of the largest silver mines in the neighbourhood of Freyherg, in 

 Saxony. This engine, which is fixed at a depth of 360 feet below the sur- 

 face of the ground, has two single-acting cast iron cylinders, each 18 inches 

 in diameter, and 9 feet stroke, to the pistons of which are fixed strong tim- 

 ber piston rods, each attached at their upper ends by a flat iron rod and 

 chain, to the opposite segments of a horizontal working beam, thus connect- 

 ing the pistons of the two cylinders, so that, when one is being moved up- 

 wards by the pressure of water underneath it, the other is depressed by the 

 weight of all the pump-rods and other mm ing parts to which it is connected. 

 The admission and eduction of water from the cylinders is regulated by slide 

 valves worked by levers and tappets. The piston-rods give motion to the 

 horizontal arms of two bell-crank levers, the diagonal arms of which move 

 the main pump-rods, working 44 pumps in two sets of 22 each placed one 

 above another, at an angle of 45 with the horizon, each dipping into the 

 delivery cistern of the pump immediately below it; this is repeated down- 

 wards for the whole series; and thus the water is raised from the bottom of 

 the mine to the point where it runs oft' by an adit. Each pump has a lift of 

 30 ft. 4 in. The duty performed by this engine is stated by Gerstner 1 to he 

 as 70 to 100. 



The author then gives a very minute account of the construction of the 

 engine, illustrating the paper by three drawings giving the general arrange- 

 ment and the detailed dimensions of all the working parts. 



Remarks. — Mr. Taylor remarked that the water-pressure engine was of 

 Hungarian origin; it was extensively used in Germany, and had latterly been 

 much improved in construction, particularly by abandoning the rude mode 

 of placing a series of pumps over each other, as had been described in the 

 paper. He believed that Smeaton erected the first engine of the kind in this 

 country. Trevithick built one about 40 years since, with cylinders of 30 in. 

 diameter. Another was erected by Mr. Fairbaim, and since then, one had 



' Gerstner, " Handbuck der Mecbanick," published at Vienna in 1834. 



