TRANSACTIONS OF THE SECTIONS. 125 



speed with less power. This principle he then proceeded to prove, and 

 to illustrate by the following case, in which the same vessel is taken 

 with different powers of engine, and the result, as regards expenditure 

 of fuel, determined first arithmetically, and then by a general formula, 

 which will enable any one to determine any particular case : — 



FAIR WEATHER. 



1,200 tons, 400 horse-power, 9 miles an hour, 216 miles per day, 1 ton 

 of coals per hour. — 2,160 miles in 10 days, 240 tons of coal. 



1,200 tons, 500 horse-power, 10 miles an hour, 240 miles per day, 

 \\ ton of coal per hour. — 2,160 miles in 9 days, 270 tons of coal. 



ADVERSE WEATHER. 



1,200 tons, 400 horse-power, 5 miles per hour, 120 miles per day, 1 ton 

 of coals per hour 2,160 miles in 18 days, 436 tons of coal. 



1,200 tons, 500 horse-power, 6f miles per hour, 162 miles per day, 

 \\ ton of coals per hour. — 2,160 miles in 13 l-5th days, 395 tons of 

 coal. 



General Formula. — Let v represent the velocity of a given steam 

 vessel in a favourable voyage ; v' the same vessel in an unfavourable 

 voyage ; v" a vessel, higher power, favourable voyage ; v" ' same in unfa- 

 vourable voyage ; p the power of the former vessel ; p' latter vessel : — 



^ p ^ ^ P v' 



in the case of equal expense, whence the highest proportion of power 

 that will be economical in fuel may be at once obtained. 



Experiments to ascertain the power of different species of Wood to resist 

 a force tending to crush them. By E. Hodgkinson, Esq. 



The specimens upon which trials have been made were turned into 

 right cylinders, about one inch in diameter, and two inches long. The 

 apparatus used to crush them has been described by Mr. Hodgkinson 

 in an account of his experiments on cast iron, published in the Trans- 

 actions of the Association. The crushing surfaces were perfectly 

 parallel, and the body to be crushed had its ends bedded firmly against 

 them, the force being applied in the direction of the fibres. The spe- 

 cimens broke by sliding off in a constant angle, dependent on the nature 

 of the material, as the writer had found to be the case in cast iron and 

 other bodies, showing that the strength in any particular species of bo- 

 dies is directly as the area of the section. Great discrepancies were 

 found when the w^oods were in different degrees of dryness — wet tim- 

 ber, though felled for a considerable time, bearing, in some instances, 

 less than one half of what was borne when dry. These experiments 



