66 



Tilt; CIVIL ENGINEER AND ARCHITECTS JOURNAL. 



[February, 



jacket, wliicli is filled with stoain from the boilers, and there is 

 another jacket, or casing of boards, the interval being filled in with 

 ashes, 17 to IS inches in thickness; all the steam-pipes are also well 

 cased with patent felt, or ashes in boxes. 



The following particulars will show the working of the engine for 

 I'A weeks, dining «hich period it worked 2,'Jil3l hours, and made 

 1,U12,3J3 strokes, at the average rate of 5-77 per minute, it raising 

 i:),'.ls-2,'.142 barrels of water, (of 360 lbs. each barrel,) 112 feet 

 inches high, with the consumption of 301 Ions, la cwt., 1 qr., 

 (^ S10,3-islbs.) of coal of inferior quality, being the refuse or screen- 

 ings of Newcastle coal, which has passed through a screen of |-inch 

 thick mesh. By adopting the method of slow combustion, they are 

 thus enabled to use the screenings, which costs only 17s. per ton de- 

 li\«red, whereas the superior coal required for rapid combustion, 

 would cost 23s. or more. 



During the same period, a condensing engine of the ordinary con- 

 struction made by Boulton and Watt, with a cylinder 80 inches 

 diameter and stroke 8 feet, with a pump 27J inches diameter and 

 stroke 8 feet, worked 1,345^ hours made 1,152,424 strokes, raised 

 S,416,3S5 barrels of water, and consumed 275 tons, 17 cwt., 3 qrs., 

 (= tj 17,988 lbs.) of coal as above. 



The Cornish engine works constantly under the same pressure, 

 while the pressure in the Boulton and Watt engine is constantly vary- 

 ing, never exceeding the former, but on the average, less. 



The Cornish engine worked night and day during the above 

 period, with occasional stoppages, while the ordinary engine worked 

 by day only; but the work of two other engines, on Boulton and 

 Watt's construction, which worked night anil day during the cor- 

 responding weeks of the previous year, was as follows : — They 

 worked for 2,9381 hours, and made 2,U08,43Ui strokes each; they 

 raised together 9,309,362 barrels of water, and consumed 568 tons, 

 1 cwt., (= 1,272,432 lbs.) of bent coal. 



Before the Cornish engine was erected, the East London Water 

 Works Company had, in addition to the water-wheels at their Strat- 

 ford and Lea Bridge Stations, four steam engines, besides an extra 

 one, which worked during the summer months : — viz. two engines of 

 30-horses power each, which worked 24 hours ; and two of about 95 

 horses power, which worked, upon an average, 12 hours per dwm, 

 the extra one was of 70 horses power, and worked occasionally in 

 the sunnner. The consumption of coal amounted to 3,426 tons per 

 annum, which was about i,'3,700., while the present engines, viz. one 

 Cornish engine, working 24 hours per day, and averaging six strokes 

 per minute, and one large Boulton and Vatt engine, working 60 hours 

 per week, calculating from the IS weeks' consumotion for both engines, 

 the annual consunqjtion will be 1,941 tons, whicTi cost l7s. per ton, or 

 .t' 1,649. 17s., thus effecting a saving of i'2,050. per annum. 



if 6(),4431bs. be taken as the actual weight lifted at each stroke, 

 (independent of friction and resistance of the engine,) and multiplied 

 by 9 feet, the average length of the stroke of the pumj), it will give 

 597,987 lbs. lifted one foot high at every stroke, if this quantity be 

 multiplied by the number of strokes, the engine performed during 

 the eighteen months, and divided by the consumption of the fuel 



during that period, it will give : (i^i^^^-Mlr^^-?!) 747,054 ibs., 



8 lU,o48 

 us the useful tffecl, raised one foot high by 1 lb. of coal or 70,223,0761bs., 

 by one Cornish bushel of 9 libs, of coal. It should be observed, that 

 the amount of coals herein given, includes the coals used to keep up 

 the steam whenever the engine stopped during the period men- 

 tioned. 



In order to secure themselves against receiving inferior coal, the 

 Directors have entered into a very peculiar contract (which we would 

 recommend to the notice of other companies) with their coal merchant 

 to supply them with coal of the same quality throughout the year, he 

 guaranteeing that above 73 million poiuids of water shall be raised 

 one foot higli by the consumption of 94 lbs. of coal, which is equivalent 

 to about 24 lbs. [ler horse power per hour; or in case of the average 

 duty of the coals not amounting to so much, a proportionate reduction 

 is to be made in the amount to be paid to him. 



We trust the foregoing statement will prove interesting to the 

 readers of our Journal. We should have been pleased if we could 

 have presented engravings of this engine to our readers, but we do 

 not so much regret the want of them at present, as we should if Mr. 

 Wicksteed had not informed us that he intends to present complete 

 drawings of the engine and boilers to the Institution of Civil Engineers, 

 with a report, as soon as he has obtained some f irther facts which he 

 deems of the utmost importance, namely, the actual quantity of water 

 evaporated by a given weight (jf coals, the (piantity of water passing 

 through the cylinder in the sliape of steam to produce the eii'ects stated, 

 and in addition also, the same facts as regards a Boulton and Watt 



engine, that a fair comparison may be made between the two systems 

 of expansion and non-expansion, and also to prove liow much is due 

 to the superiority of tlie boilers (if any), and how much to the mode 

 of uxtng the steam when generated. 



The system adopted in Cornwall of reporting to the public every 

 month the duty of the engines, has, we have little doubt, led, by 

 exciting emulation, to the perfecting of the expansion engine, and if 

 in other parts of England the same system were adopted, there is no 

 doubt the public would benefit, as well as those manufacturers whose 

 desire it is to make the best engine, and we therefore offer to those 

 interested in the subject to pul)lisli in our Journal the reports forwarded 

 to us. We have little doubt of having a monthly report of Iht Cornish 

 engine, and we should like to have reports of others to compare 

 with it. 



MEMOIR OF DAVIJvS GILBERT, ESQ. 

 (From the West Britnn.) 



Davii;s Gilbert, E.sij.. D.C.L., late President of the Royal Society, was 

 Hon. F.K.S.E., F.A.S., F.L.S., F.G.S., F.R.A.S., President of the Roj al Geo- 

 logical Society of Cornwall, Hon. Member of must of the iirovincial societies 

 in llie Kiomlom, and of many on the CVinlincnt; lie was also many years 

 Member of Parliament for Bodmin, our county to« n, and was truly known 

 as the Father of liiilish Science. He was the only son of the Rev. Eilwaril 

 Gidcly, of St. Erdi, the representative of the vesjicctutile family of (Jidily, of 

 Nanteavallan, by Catherine, only daughter and heiress of Henry Davies, 

 Esq.. of Tredrea, only survivor of the ancient house of Davies. throuKli 

 whom he was connected with the noble family of Sandys, and that of Noycl 

 of which the well-known Attorney-Genera! was a member. 



^VIlen a child, his precocious t'llenis were the theme of the extensive circle 

 uilh which his tathcr, as chairman of Quarter Sessions, associated. His 

 preliminary education was conducted at home; and at a very early age he 

 cuntractccl an intimacy, which continued until death, with the Rev. Malachy 

 llitchcns, vicar of , St. Hilary, a gentleman of high and well-ileserve.l cele- 

 Ijrity as a niathcmalieian and aslroncjmer, and as editor of the "Nautical 

 Almanac." This adiuiiintance, without doubt, materially added in dcter- 

 minini; his mind to mathematical pursuits, in which he was afterwards so 

 greatly distinganshed. His aca^lemic education was received at Pemlirukc 

 College, 0.>;ford, to the funds of which he has been a liberal donor. 



The introduction of Mr. Watt's celebrated improvement in the steam-en- 

 gine into the Cornish mines, and the disimtcs between that great mechanical 

 philnsopher and the late Mr. Jonathan Hornblowcr, of Penryn, as to the 

 economy and mode of applying the principle of working steam expansively, 

 and which has since been carried to greater extent, and with a more remark- 

 aide economy of fuel in this county than any where elst^ early attracted 

 Mr. Davies Gidcfy's attention ; and the various subjects embraced in its per- 

 fect development formed a noble field for the employment of his rare mathe- 

 matical attainments. The e.\pansive action was employed by Mr. Watt in a 

 single cylinder, but Mr. flornblower used two. It was, hoivever, far more 

 readily made out in theory than it was acknowledged in practice, that by 

 the use of one cylinder only the same mechanical advantage is obtained, 

 avoiding )he additional friction which a second cylinder would entail. The 

 ])lan of Mr. Hornblowcr was, after a silence of several years, revived by Mr. 

 Woolf: but it seems by general consent and experience, and by universal 

 practice, to be now admitted that Mr. Watt's is the prel'eiable mode. 



Mr. Davies Giddy was solicited by the county at large to take an active 

 part in the determination of the duty performed by Mr. Watt's engines — a 

 task for w hich his genius and inclination peculiarly fitted him ; and in con- 

 junction with the late Captain 'William Jenkin. of Treworgie, he made a sur- 

 vey of all the steam-engines then working in Cornwall. 



An indifference to the labours of anthorship, provided the results of his 

 inquiries were available to the public without appearing in print, prevented 

 the investigations of these most important subjects from seeing the light in 

 an authentic form until lately ; the first iti them appears in the Philosophical 

 Transactions of the Royal Society in 1827— the second still more recently. 



One ol the most laborious and practically useful works which has distin- 

 guished that rich storehouse of intellectual wealth, the Philosophical Trans- 

 actions of the Royal Society, is a paper by Mr. Gilbert, " On the Properties 

 of the Catenary Curve." This fine example of mathematical inquiry was 

 published whilst the celeLrated engineer Telford was preparing his materials 

 for the construction of that stupendous national work, the Menai bridge; 

 and it affords one of the finest tributes on record to the labours of the philo- 



