MECHANICS AND USEFUL AKTS. 65 



cleaned and put in the best possible order. The engineer was then directed 

 to run for one week, carefully weighing his coal, as well that used in getting 

 up steam as the consumption to do the work. The result of the week's ex- 

 periment was an average of 750 Ibs. of coal consumed per day, the quan- 

 tities varying from 25 to 50 Ibs. per day according to the work to be done. 

 "We should here state that the engine had also been put in good repair. At 

 the expiration of the week, having satisfied ourselves of the average consump- 

 tion, we directed the copper casing to be tied around the boiler ; the engi- 

 neer continuing as before to weigh carefully the fuel consumed. 



The result of the first week's consumption after the copper was put on was 

 475 Ibs. per day. The second week and each succeeding week showed an 

 average of 450 Ibs. per day. The consumption of fuel and the comparative 

 advantages gained by the copper covering, would therefore be represented as 

 follows : 



Consumption without copper casing .... 750 Ibs. 



Do with copper casing ..... 460 ,, 



Saving 300 Ibs. 



or 40 per cent, of the ordinary consumption of fuel in the furnace. 



This result was to us, who paid the coal bills, highly satisfactory. But 

 apart from its economy, it presents an interesting subject for consideration. 

 That a steam boiler does not radiate 40 per cent, of the heat received must be 

 evident. If it did, inclosing the boiler in wood or other non-conducting sub- 

 stances would show an equal saving in the consumption of fuel. Yet such is 

 not the fact. "We are informed by practical men that a wooden case effects a 

 saving of from 5 to 10 per cent. It is also stated that a sheet iron casing will 

 effect about an equal saving. The saving of 40 per cent, by a copper casing 

 wrapped loosely around the boiler is a fact for the consideration of the curious 

 and philosophical. 



BLANCH ARD'S TIMBER BENDING PEOCESS. 



By Blanchard's timber bending process (see Ann. Sci. Dis. 1855, p. 38), now 

 effectually proved and established, it is stated that the strength of the wood 

 is increased at least seventy-five per cent, at the point where strength is 

 most required. The curve, moreover, never relaxes. The timber, as in the 

 old process, is first subjected to the influence of steam, which softens the 

 whole mass, and puts it in a fit state for the action of a machine. The prin- 

 ciple of bending, as employed in this new application, is based on end- 

 pressure, which, in condensing and turning at the same time, destroys the 

 capillary tubes by forcing them into each other. These tubes are only of use 

 when the tree is growing ; and their amalgamation increases the density of 

 the timber, the pressure being so nicely adjusted that the wood is neither 

 flattened nor spread, nor is the outer circumference of the wood expanded, 

 though the inner is contracted. Now, the error of the former process, as 

 expounded by competent judges, has arisen from the disintegrating of the 

 fibre of the wood by expanding the whole mass over a rigid mould. "Wood 

 can be more easily compressed than expanded ; therefore, it is plain that 



