J 82 1.] New Scientific Books. 237" 



and free from jar or concussion. The engines have worked repeatedlj 

 for days at the rate of \2 and IS strokes a minute, and the whole has 

 gone as smoothly as if a fly wheel regulated the impulse. 



The effect of the first of these engines, or, as it is called in Cornwall,, 

 the duty, has been regularly calculated by the person appointed for that 

 purpose, and has been published in the monthly report. 



It was found to have consumed about 3,8(){) bushels of coal in 35 

 days, or 11 1 bushels per day. and the effect had been that of raising 

 38,5()(),000 lbs of water by each bushel of coal, which is rather more 

 than was done in the same period by any engine of similar construc- 

 tion. 



It may be worth mentioning the weights of some of the principal 

 parts of one of these large machines. The cylinder, exclusive of the 

 cover and bottom, weighs about 1/4- tons, in one piece ; it is surrounded' 

 by a case of still greater dimensions. The beam with its gudgeon 

 weighs nearly 25 tons. 



The pump rods in the shaft are the largest mast timber that could 

 be procured, and are 16 inches square to a considerable depth in the 

 chait; when the whole are attached, they will weigh, with the iron 

 plates which connect them together, nearly 40 tons. 



When it is considered that to this latter weight is to be added that 

 of the column of water, and one half of the beam, we shall find nearly 

 100 tons on one side the centre, and of course a corresponding pressure 

 on the other side to counterpoise it; so that there is suspended on the^. 

 gVidgeon, and moving freely upon it, nearly 200 tons. 



The piston frequently passes through 240 feet every minute, and 

 gives a correspondmg velocity of motion to this immense mass of mat- 

 ter, which is yet regulated with a precision that is astonishing, and 

 which acts without concussion, and without disturbance, to the various 

 parts of the machine. 



There are many most ingenious improvements in the construction, 

 and the arrangement is simple and complete. The whole reflects great 

 credt on the skill and ability of Mr. Woolf, to whom Cornwall has 

 before been indebted for the introduction of some of the most important 

 improvements in steam engines that have benefited the mines in later 

 years. 



The works at the Consolidated Mines were only commenced in Jan. 

 1819, and it is probable that in a few weeks the water will be all 

 pumped out; so that this, with the extensive erections for various pur-- 

 poses on tlie surface, which are such as to render it probably the 

 largest and most complete mining establishment in the world, have been 

 executed in two years. 



I 



Article XVIII. 

 NEW SCIENTIFIC BOOKS 



PREPAllING FOR POBUCATIOjr. 



Dr. Leach has nearly completed his Synopsis of British Mollusca. 

 Otto Von Kotzbue's Narrative of a Voyage round the World, in the 

 Russian ship llevric, is translating for the press. 



