202 Report on Steam Cultivation. [Claeke. 



steam cultivator for maintenance in a course of years can only 

 be arrived at from the history of a great number of machines, 

 extending over a protracted interval of time ; and ultimately, 

 when steam cultivation is a quarter of a century older, we shall 

 be able to say such and such an appaiatus has so many acres of 

 work in it, just as railway managers can assign the total number 

 of miles that a locomotive is expected to run. We have reflected, 

 however, that the arbitrary and gratuitous allowances for "wear 

 and tear " are separable into two distinct items — " repairs " and 

 "depreciation" in value. Steam-ploughs have been in existence 

 long enough to give us trustworthy data for the first ; and, there- 

 fore, instead of endeavouring to get one general percentage for 

 repairs, we state them at what they really are — whether con- 

 sisting of the ordinary renewal of wearing parts (as rope, shares, 

 pulleys, brasses), and parts consumed in working (as grate-bars, 

 fire-boxes, &c.), or of replacements arising from accidental or 

 other breakages — of course distinguishing between these and 

 additions of improved parts, which are simply augmentations of 

 the first cost of the machinery. There is left an uncertain item 

 of gradual " depreciation " in value of the framework, &c., or 

 those main parts of the apparatus which are not constantly main- 

 tained at their original worth by renewals and replacements. 

 And we have to ascertain what is the average length of life of a 

 steam-plough. Where so much depends upon the amount and 

 character of the work done, the intervals of rest (and rust), the 

 quality of the water used, the care and intelligence of the engine- 

 driver and workmen, and also upon the inherent difference 

 between two engines turned out of the same workshop (says Mr. 

 H. Evershed in his Essay ' On the Wear and Tear of Agricul- 

 tural Steam-engines,' Journal, vol. xxiii.), it is impossible to fix 

 upon any general percentage likely to be true in a majority of 

 cases. Mr. R. Vallentine, in his paper on ' The Comparative 

 Advantages of Fixed and Moveable Steam-Power ' (Journal, 

 vol. xxiii,), does not attempt to separate repairs from deprecia- 

 tion, but lumps them together in " cost of maintenance " at fully 

 20 per cent. ; which, however, he says, is too much if applied to 

 the work of thrashing on one farm. Mr. Frere (Journal, vol. xxi.) 

 does make the distinction, allowing, after all repairs are paid for, 

 10 per cent, for depreciation, besides 5 per cent, for interest. 

 Mr. Turnill (quoted by Mr. Frere), from his experience with 

 three portable thrashing-engines at continual contract-work, 

 thinks that the engines will be unfit for use in 10 or 12 years, 

 and that 10 to 12i per cent, should be set down for depreciation. 

 Mr. Evershed, after stating the repairs of twenty portable engines, 

 computes the depreciation in this way : — A ten-horse portable is 

 purchased for 290/., what will it be worth in 10 years' time? 



