420 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



[December, 



llie Cornisli oi>gincs. wliich Mas so groat tiiat the pressure of . steam in the 

 cylinder, wliicli wou'd amount td 7,500 ll>. per square inch, would raise nearly 

 double the amount of any in the neighbourhood, chiefly from the advanlaffe"s 

 of the exnan>ive principle adopted in the Cornish engine. Mr. Fairbairn then 

 proceeded with liis paper, of which the following is an abstract : — 



" The steam engine performs so important a i art in almost all the transac- 

 tions of man, where great power is required, that the progressive nnprove- 

 ments of this mighty agent, indispensable to the miner, must be regarded 

 with interest by all. By the geologist its improvement will be looked at with 

 additional pleasure, since by its means he is enabled to explore the earth to a 

 much greater depth than he otherwise could have done. For this reason. I 

 liave thought it might not be out of place to give here some account of the 

 progress of the steam engine during the last 120 years, mentioning the dates 

 of its leading improvements. 



" From the time of Savery and Newcomen, in 1707, to that of Beighton, in 

 1717, it remained stationary, till 1769, when Sme ton introduced considerable 

 improvements U|ion atmospheric engines, the average duty from fifteen of 

 which amounted to 5,590,000 lbs., lified one foot high by a bushel of coal* 

 These improvements continued ; and the duty, in 1772, was raised to 9,450,000 

 lbs. 



" Mr. Watt's improvements commenced in 177G, when the average duty 

 was declared at 21,600,000— more than double that of .Smeaton's ; and, during 

 the years 1778-9, it was still further increased. 



"In 1779. and from that to 1788. Mr. Watt introduced the improvement of 

 working steam expansively, which raised the duty to 26,600.000. From 1788 

 to 1812, few, if any improvements were made in the Cornish engines; and, 

 provided we except the plunger pole, which was introduced about this time, 

 I question whether the Cornish engineers and miners did not retrograde rather 

 tlian advance during a period of tw enty-lbur years. 



"In 1814 considerable advances were made, which raised the duty to 

 32,000,000 lbs. During that year, Woolf 's engine, with two cylinders, was 

 introduced, which again advanced the duty to 54,000,000 lbs. 



" Mr. Woolf, above all others, did most for the Cornish engines, by show- 

 ing the advantages peculiar to high pressure steam, and prepared for suljse- 

 quent improvements, wliich led to the present efiective system of expansive 

 working. 



"During a period of six y'cars, from 1814 to 1820. Woolf 's double cylinder 

 engine maintained its superiority, and gave a higher duty than any other. 



" Woolf 's engine, in process of time, gave way to others of a better con- 

 struction. They were intr. duced by Captain Samuel Grose, whose experi- 

 ments upon the generation and preservation of heat led to great improvements, 

 and ultimately established a new era in the history of the Cornisli engine. 



" In 1826, Captain Grose's engine, at Wheal Hope, attained a duty of 

 62,000.000 lbs. ; and, in .July of the following year, one of Mr.M'oolf "s single 

 cylinder engines performed the unpreccdented'duty of 07 million. 



" From this time Captain Grose's improvements were appreciated, and 

 generally introduced ; they led to a slill greater advance in the duty, wliich 

 this year reached as high as 87 million Ibs^ 



•■ Messrs. Lean and Brothers report the duty of a few of the Cornish en- 

 gines at this time as follow ; — 



Millions lbs. 



Wheal Towan Engine 87'0 



Wheal Hope 74 8 



Consols 676 



Binner Downs 63 5 



Consols 61-7 



Consols 61-3 



Wheal Vor 611 



Wheal Towan. (Druce's) 59"4 



Consols 584 



PoUlice 57-8 



Wheal Vor 51-9 



These give a mean duty of sixty-four millions of pounds. 

 "Nothing remarkable took place till 1834, when the duty was raised to 

 90 millions lbs Since then, it has continued to increase in the ratio of 90, 

 100, and llOmillions : and during the last meeting of tlie British Association, 

 at Glasgow, Mr. Taylor reported the present duty at the unequalled perform- 

 ance of 123. 300.593. 



" Having briefly stated the progressive improvements that have taken place 

 in the Cornish system of pumping, I would now direct the attention of the 

 society to the important results which these improvements have produced. 



" The quantity of coals consumed by all the engines w orking at the mines 

 in Cornwall, in the year 1835, was. according to Messrs. Lean and Brothers, 

 1,669,421 bushels. Now, if we compare this with the number of bushels 

 which would have been consumed to produce tlie same power iit 1814, we 

 should have, for the consumption at that iicriod, 4,049,878 bushels, making a 

 saving of 99,18'; tons; which taken at n.s. per ton, (the price of coal in 

 Cornwall.) we have the enormous saving of £84,308. 



" From the above facts, it cannot be doubted, that the improvements in 

 steam engines, and the consequent saving thus effected in the consumption of 

 fuel, are matters of deep importance. Lven in districts where coal is cheap, 

 it is a consideraticm well w orthy of attention ; and we are assured by geolo- 

 gists, that the coal of this country, although abundant, will not last for 

 ever." 



In the cotirse of a very interesting discussion which followed the reading of 

 the paper, Mr. l''airbaim said, he might mention that so great was the saving 

 from the improveil system of w orking tlic Cornish engines, that it was not 

 improbable that, in this neighbourhood, we might come back to the old sys- 

 tem of power for factories- If the duty performed by the Cornish engine was 



* Duty is a teim first used liy Mr. Watt for ascertaining the comparative 

 merits of steam engines. In Cornwall it is used for determining the number 

 of millions of pounds of waler lifted one foot liigh by a bushel of coal, (,94 

 lbs. the time of lifting it not being considered. 



so much more than that of any factory engine in this district, it migli: l.e 

 desir.able to liave a Cornish engine connected with a water-wheel to drive mill 

 machinery.* 



Mr. Boothman. — Why not apply it to rotatory motion ?— Mr. Fairbairn 

 said, that it would not apply to any thing where the force required was con- 

 stant. The value of the tiling bay in overcoming the inertia of matter. The 

 Cornisli engine first raised a weight, and then, by the descent of that weight, 

 it raised the water. That was the w hole secret of the Cornish engines. 



Mr. P. Clare asked if Mr. Fairbairn had made a calculation of tlie eftective 

 force of the factory engines in this neighbourhood, so as to afford a compari- 

 son as to the combustion of coal by them with that of the Cornish engines ? 

 — Mr. Fairbairn said, he had done so. The consumption of fuel in our best 

 condensing engines here was 10 lbs. to 12 lbs. per horse power per hour, while 

 the consumption of fuel by the best Cornish engines was only 21 ll«. per horse 

 power per hour. In other s' ords. we consume four times more coal than the 

 Cornish engines in producing the same effect. The circumstance was most 

 extraordinary; but the facts were before the meeting. The returns of the 

 duty performed were regularly registered in Cornwall, and published monthly, 

 so that any gentleman might see them, in reference to any period : and it 

 would be found, that the performance of the best Cornish engines (for he did 

 not, in reference to this question, speak of the average duty) did nut exceed a 

 consumption of 2i lbs. of coal per horse pow er per hour. 



A Member asked whether there was not some doubt as to the accuracy of 

 the calculations of the duty performed by the C'ornish engines, and as to the 

 mode of estimating them'?— Mr. Fairbairn said, that the calculations were 

 made upon the area of the bucket and the length of the stroke. He was aware 

 that doubts hid been expre.ssed as to the accuracy of the calculations ; but 

 they were backed by such authorities, and the returns were so numerous and 

 regular, that he thought their general accuracy could not well be doubted. — 

 The Member observed, that a small quantity of air coming up the pumps 

 would make a difference.— Mr. Fairbairn : No doubt ; but still the engine has 

 to lift this great weight of all the pumps and iron work, and the plungers, 

 which must lie lifted by the force of steam. He had a return from Mi\ Wick- 

 steed, of the East London Water Works, which was not a pit at all ; but the 

 Cornish engine there was used to raise water for the supply of the eastern 

 [lart of London — which return gave a duty of 118,552,475 lbs. raised one foot 

 nigh ; the consumption of fuel being 2 4 lbs. of coal per horse power per hour. 

 Of course he did not speak of the duty performed by these Cornish engines 

 from his own knowledge, but he had every reason to believe the returns sub- 

 stantially correct. — The Member said, he believed some doubts liad been re- 

 peatedly' thrown on the method of calculation. — Mr. Fairbairn said, that some 

 years ago he had Ijeen present at a discussion on the subject in the .Society of 

 Civil Engineers, when great doubts were expressed, but further documents 

 were brought forward to prove the accuracy of the calculations. However, 

 taking the consumption of fuel by the C'ornish engines to be 3 lbs. per horse 

 power per hour, that was a very great difference, as compared with our factory 

 engines. 



Mr. Eaton Hodgkinson thought there had undoubtedly been great improve- 

 ments made in the Cornish engines, chiefly the result of the adoption of the 

 expansion of steam, wh ch they had not been used to any great extent in this 

 neighbourhood, at least till very recently. Whether the returns Kere quite 

 accurate or not, no one could doubt that the improvements were immense. 

 He thought the p'an of making the engine to lift the pump-rods only, and 

 then the descent of the pump-roils lifting up the water, seemed to be a con- 

 siderable improvement in adaptation. Again, whether Mr. M'oolf's plan of 

 the expansion of steam, or that of Mr. M'att, expanding it in the s.ame cylin- 

 der, and cutting it off when at a distance of one-fourth or one-fitth down, 

 were adopted, (and it was a question as to wdiich plan was the best,) in l:oth 

 cases there was a great improvement upon former methods. These improve- 

 ments had a strong bearing upon geology, for were it not for these engines, 

 they could not investigate the strata in mines, for the water would drive them 

 out or drown them. These engines, by draining lakes, might enable the 

 geologist to obtain a great deal of information he must otherwise be wiihojt. 



PROCEEDINGS OF SCIENTIFIC SOCIETIES. 



BRITISH ASSOCL\TION FOR THE ADVANCEMENT OF SCIENCE. 

 Tenth Meeting. — September, 1840. 



fFrom the Aihenmum.J 

 Section G, — Mechanical Science. 



•Mr. James Milne gave an account of an instrument termed a Gas Regulator, 

 of his invention, by means of which the length of the flame is equalized, 

 notwithstanding the variations of ]>ressure that occur, and a considerable sav- 

 ing in the consumption of gas is effected. 



Mr. Coles on Railway Carriages. — Mr. Coles proposes to introduce friction 

 wheels ; and that, excepting the first and last carriage in the train, the car- 

 riages should run on two wheels. He also proposes a step-rail at the cur\cs 

 or bends. 



" On the Turbine Water-wheel." By Prof. Gordon. 



The fundamental principle upon which the construction of the Turbine- 

 Foitmegron is based, is that by which the maximum of useful effect is obtained 

 from a given fall of water, depending on the relative velocity of the water 

 and its recipient, which ought to be such that the water enters the wheej 



* See Mr. M'icksteed's report in the Journal for January last, page 7' — Ed. 

 C. E. and A. Journal. 



