50 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



[February, 



of the various arts, and vole sums for the encourngernent of any de- 

 sirable object, in connexion therewith ; such, for example, as for the 

 prosecution of experiments in the preparation of colours, the manu- 

 facture of stained-glass, or for the purchase of particular pictures, 

 worthy of national regard. 



During the meeting the various local collections would be thrown 

 open to inspection; conversazioni would be held; and i.ther means 

 adopted to bring men into contact with each other, on one common 

 ground. One ot the first points to be achieved by the united sections 

 would be, to obtain an able and correct report of the progress of Art 

 in England, Ireland, and Scotland, for the last fifty years — a task to be 

 fulfilled satisfactorilv only by the joint co-operation of men in all parts 

 of the country. This report would afterwards be continued from year 

 to year, under its various heads, and could not fail to prove a work of 

 the highest interest and value. It is not here attempted, however, to 

 point o\it what could be done by a society organized on the footing 

 suggested : its power of effecting much good must be apparent to all, 

 and needs hardly to be insisted on. The writer is contented simply, 

 but with great earnestness and but one object, — namely, strong desire 

 to serve the cause the Art (the cause of morality and public good), to 

 state the ))roposition, in the hope that others of more ability, influence, 

 and leisure, may view it as it has appeared to him ; and be induced to 

 carry it into execution, etliciently and forthwith. 



George Godwin, Jun. 



Pelham Crescent, Bromplon, 

 January, 1841. 



WOOLF'S DOUBLE CYLINDER ROTARY ENGINE. 



SiR—In your number for December last, I read a very interesting 

 account of the communication made at the annual meeting of the Man- 

 chester Geological .Society, by Mr. William Fairbairn; Mr. Fairbairn 

 paid a just triliute of praise to the late Mr. Woolf, by acknowledging 

 the real services rendered by his single engine in Cornwall particularly, 

 and to science generally, "in consequence of the undoubted progress 

 made by his application of high pressure steam employed expansively. 

 Mr. Fanbairn's remarks were the more gratifying, inasmuch as the 

 exertions of Mr. Woolf appear generally to be in a state of perfect 

 " oubli," although there can be very little doubt, that he was the first 

 after Mr. Watt to give an impulse to the progress of the Cornish en- 

 gine, and that much more is due to him than has been generally ac- 

 knowledged, this circumstance reflects honourably on Mr. Fairbairn's 

 proceeding, to whom much praise is due for his just observations, and 

 for bringing before society a name that is little known, and more 

 honoured abroad than at home. 



The principal object of my present application to you is to request, 

 that you will give place to "the following observations relative to Mr. 

 Woolf's double cylinder rotary engine, which being but little used in 

 England, has been hitherto very much neglected. I am of opinion 

 that this engine, if better known, and if patronized by engineers of 

 enterprising genius, and in "good repute," would very generally be 

 preferreil to every other known system : I speak after having had long 

 and solid experience, and having been in the habit of actual observa- 

 tion abroad, on many hundreds of engines upon different systems, I 

 can very confidently assert, that Woolf's engines when properly made, 

 ■will work quite as well as any other engine, and will perform the same 

 duty with a consumption of coal that will not e\ceeAjirc pounds per 

 horse power per hour; I have seen many engines of this description 

 doing very satisfactory duty with less. 



I have had several opportunities of conversing with manufacturers, 

 who having had low pressure engines, have contracted with engineers 

 to have their cylinders and boilers replaced for the purpose of apply- 

 ing Woolf's principle, and they have invariably declared that they 

 have cfl'ected a saving of upwards of one half of the fuel. 



I will cite for example an engine on Woolf's principle erected in a 

 mill for rolling zinc and lead, and for drawing pipes. The dimensions 

 of this engine were as follows. 



Area of small cylinder, 2U7'39 square inches. 



Stroke of tmall piston, 1-.59 feet. 



Speed of piston per minute, 176-34 feet. 



Area of big cylinder, tiliu- square inches. 



Stroke of big piston, G-3 feet. 



Speed of piston per minute, 242' feet. 



Pressure of steam in the boiler tending to escape into the external 

 atmosphere, 40 lb. per square inch. 



The capacity of the small cylinder naturally determines the quan- 

 tity of steam that the boilei must supply, and allowing that the cylinder 

 fills with steam of an clastic power equal to that iu the boiler, and ad- 



mitting that the big cylinder produces the same effect as the cylinder 

 of an ordinary low pressure engine, the total power of the above 

 engine may be computed in the following manner. 



Area of each cylinder in square inches, X pressvtre of steam per 

 square inch, X speed of piston in feet, and (he product divided by 

 3;30U01b. one foot high per minute per horse power, will give the 

 computed power of each cylinder. 



^ „ ... 207-39X4OX17G-34 ..„„„„ 



Small cyhnder -— — ^--- = 44-32 H. P. 



Big cylinder. 



330U0 

 660 X 10 X 242 

 33000 ' 



= 48-40ttP. 



Computed power of the engine 

 If we deduct for friction one-third 



= 92-72 H. P. 

 = 30-92 



:61-S H.P. 



The eftective power will be 



I will call her a CO horse engine. 



To ascertain the quantity of coal this engine will burn, it will be 

 requisite to determine the quantity of water that must he evaporated, 

 to produce a sufficient supply of steam, which can- be done as follows : 



The area of the small cylinder in sq. inches X by the speed in feet 



144 ~ 



capacity of small cylinder in cubic feet per minute. 



•207-39 X 17G-34 ..., , . , , .... 

 ;= 2o4 cubic feet, representmg the space occupied 



by the action of the piston in one minute, and if we add thereto one- 

 tenth for the steam ways, and the space between the top and bottom 

 of the cylinder and the piston, we shall find that the boiler must sup- 

 ply per minute, 254 -1-25-4=:; 279-4, or say 280 cubic feet of steam, 

 under a pressure of 40 lb. per square inch, and per horse 280 X 60 =: 

 1G800 cubic feet of steam. 



One cubic foot of water converted into steam of an elastic form 

 equal to 40 lb. per square inch, will occupy in the shape of steam about 

 520 times the original volume, consequently the ItiSOO cubic feet of 



IfiftOft 

 steam that will be requisite per hour, will be the produce of =: 



32-31 cubic feet of water per hour. 



32-31 X f>2-5 = 2020 lb. avoirdupois. 

 -Suppose 1 lb. of coal to evaporate 8 lb. of water, and Messrs. Parkes 

 and Wicksteed have proved that more can be done, but allowing 8 lb. 

 as a fair proportion, the hourly consumption of coal would be 



= 252-5 lb. of coal per hour. 



8 



and 



2.''>2 



: 4-2 lb. of coal per hour per horse power. 



I am aware that nothing in the above computation has been allowed 

 for leakage by the piston, but with a good and true cylinder, and a well 

 fitted piston, very little steam will pass — and if 5 lb. of coal are allow- 

 ed instead of 4-2 as above, the difference will more than compensate 

 for any loss of this kind. 



The above engine was for a considerable length of time doing only 

 40 horses work, and her average consumption of coal was 1 hectohter, 

 or 80 kilogrammes of coal of a mediuui quality per hour, or 2 kilo- 

 grammes ^er hour, and per horse power— 2 kilogrammes = 4-41 lb. 

 avoirdupois. 



Should you consider these remarks to be worthy of a place in your 

 very useful Journal, you will nuich oblige, 



Your very humble servant, 



London, Jan. 14, 1S41. H. H. E. 



Imporlmil lo BuihUrs and others.— U may not be generally known tliat an 

 Act of last Session imjiospd certain restrictions on the mode of building 

 chimneys, w illi ilie view of rendering climbing boys unnecessary in cleansing 

 flues. It is thereby enacted that after tlie passing of the Act. •' all partitions 

 between :iny ebimfiey or flue shall be of brick or stone, and at least eqiial to 

 half a brick in thickness," such partilion to lie of sound materials, " and the 

 joints of the work well filled in witb good mortar or cement, and rendered or 

 stuccoed » uliin ;" ■' that such cliimnev or (hie in any wall, not being a cir- 

 cular chimney or due 12 inches in diameter, shall be in every section of the 

 same not less than 14 inches by 9 indies," The .angle at which it is lawful 

 to build any chimney is also determined. Another clause enacts " that from 

 and aficr the first day of July, iu (lie year 1S42, any person who shall compel 

 or knowingly alhiw any child, or young person under the age of twenly-one 

 years, to ascend iir descend n chimney, or enter a flue, for the purpose of sweeii- 

 ing, cleansing, or coring the same, or for extinguishing fire therein, shall be 

 liable to a penalty, not mure than ten pounds, or less than five pounds. 



