we consider it imprudent to cause the animals to be conveyed, lest serious accidents should befall them. We have made no addition to the useful effect for these three planes, for the difference either between the horse exerting a force of 12.27 lbs.or walking one-half of the entire distance, as on the two last planes and that of his exerting a force of 37.5 lbs. when drawing the empty carriages along the level. It will be perceived that the friction of the empty carriages is estimated at the 150th part of their weight; which however is not precisely the case, it being rather more on account of resistance to motion increasing in rather less ratio than weight; although such difference is scarcely perceptible in practice. We shall now proceed to explain the method of estimating the performance of horses, when they are employed upon a level, upon ascending, and descending planes. For the level plane: The power resist. on the level=the weight drawn along the level. For the ascending plane : The pr.Xwt. drawn upon the level_the weight drawn up resist. on level+gravity of plane the plane. For the descending plane : The pr.Xweight drawn on the level resist. on level-gravity of plane the plane. -the weight drawn down Note. The effect produced upon planes of the above description may be calculated decimally with great facility, as shown in the explanations to the following tables of resistance, in the latter part of the present chapter. EXAMPLES. ; 1. Suppose a horse be employed on a gradient ascending at the rate of two inches per chain what will be the result of his day's work? power, friction, &c., as stated in p. 78. Pr. 150×150=22,500 lbs., the weight drawn upon the level, and two inches per chain-1 in 396 orth part of 22,500 lbs. is to be added to the friction on the level, for gravity of plane. th. pt. 22,500÷150-150 lbs., friction on the level. and, 22,500÷396= 56'82 grav. of plane. and, 150X22,500 206.82 206.82 lbs. total resistance. 16,318.53 lbs. the weight drawn at one timeX12 mls. trav. loaded=195,822 lbs. gross 4th for wgs.=146,866 lbs. the weight of earth drawn one mile per day. 146,866-2240=65 56 tons drawn 1 mle. per day. 146,866÷3136=46.83 cub, yds. drn. 1 mle. per day. 1.281 pence per ton per mile. 7s.÷65.56 7s. 46.83 1.794 pence per cub. yd. per mile. 2. If a horse be employed upon an inclination, descending at the rate of one and a half inches per chain, or 1 in 528; what will be the result of his day's work? Power, friction, &c., as in the preceding example. Pr. 150×150 22,500 lbs. the weight drawn upon the level; and for the plane descending 1 in 528;th part of 22,500 lbs. is to be deducted for gravity of plane, from the friction on the level. 150 lbs. friction on the level. and, 22,500-528 42.61 gravity of plane. then, 150X22,500 down the plane. 107.39 lbs. total resistance. =31,427.51 lbs. the weight drawn On the level plane, the horse returns with empty waggons amounting to one-fourth of the gross weight in the loaded direction, or 5625 lbs._but it would require additional power to draw one-fourth of the above descending load, (31,427.51 lbs.,) up this plane of 1 in 528. Therefore, we must estimate a number of waggons drawn up this plane equivalent in weight to 5625 lbs. drawn on the level; which, being added to the gross downward load, will be equal to a whole journey to and fro, on the level. Now, a power of 150 lbs. draws 22,500 lbs. upon the level; hence a power of 37.5 lbs. will draw 5625 lbs. upon it. 5625÷150th pt.=37.5 lbs. friction on the level. 5625-528 7.1 gravity of plane. 44.6 total resistance. then, 44.6 37.5 : : 5625 4380.84 lbs. the weight of the empty waggons drawn up the plane. and, 31,427.51+4380·84-35,808 lbs.X12 miles= 192 tons the total weight drawn one mile per day. The weight of the earth waggons being to th of the gross weight when loaded; 4th of this 192 tons will be absorbed by returning the empty waggons, and also another fifth by the waggons carrying the downward load; leaving 115 tons, or 82.21 cubic yards of earth, drawn down the plane one mile for the horse's day's work. The weight of empty waggons drawn up the plane equivalent to 5625 lbs. drawn along the level may likewise be found in the following manner :150 lbs., friction on the level, and and, 192.61 42.61 gravity as before. 192.61 lbs., total resistance. 150 lbs. pr. : : 5625: 4380 lbs. the weight of the empty waggons drawn up the plane of one in 528, as on the eighty-fourth page. CHAPTER VI. HAULAGE, CONTINUED. Advantages and Disadvantages of employing locomotive and fixed machinery, for the removal of earth-works-Locomotive and Stationary Engine planes -Elucidation of that plane upon which the maximum Effect is produced by Animal power-Method of estimating the Average distance of leading earth-work-Tables exhibiting the Resistance opposed to the motion of Carriages upon various Inclinations of Ascending and Descending planes; also Examples explanatory of their use-Tables of the Resistance of various kinds of Roads, and Granite Tramways-Tables showing the comparative Weights drawn, and the corresponding Expense upon such roads-Proper Inclination for a Descending Trade for each kind of road-Effect of the Inclinations, with their relative Expense-Patent axle Grease, and Lubricating Fluid, &c., &c. The several calculations in the last chapter relate to horse power, which is chiefly used, when constructing railways, and often attended with the least expense; but where works are of great magnitude, the application of mechanical power is to be preferred. Where the blocks are imbeded in clay, or other retentive soils, in order to free the rails from the weight of the motive power or where gradients are steep-fixed machinery is indispensable. But, where hard material can be procured at a reasonable expense, to form and repair the road; or where the earth is to be drawn along permanent lines, locomotive power may be introduced successfully, as it is decidedly preferable to fixed machinery, on account of the greater facility with which it can be applied, as the length of cutting |