Pocketbook of Useful Formulæ and Memoranda
for Civil and Mechanical Engineers

222 Molesworth's pocket-book Resistance of Tbains. (Harding’» Formula.) T = Weight of train in. tons. V = Velocity in miles per hour. A = Area of its frontage in square feet. B = Its volume in cubic feet. R = Resistance in lbs. on a level. R = T (6+ -33 V) + 0025 V2A. = T (6 + -067 V) + -00002 V2B. Experiment has shown that at lower speeds the formula gives too high result«. Table showing Results op Experiment COMPARED WITH FORMULA. Velocity, Miles per Hour. Weight in '■ Tons. Resistance in Lb®. By Formula. By Experiment 16 w 40j 13-2 12-9 8’5 8'5- 21 18 16'7 12-6 25 40t 16-6 12-6 27 40$ 17-7 12-6 31 is; ' 25-4 23’4 32 14+ 27’2 22-5 34 30i 23-1 25 34 is 27-2 23’4 35 21f 26-1 22-5 39 24 31*0 30 47 31J 33-1 33-7 50 30 35'3 32-9 53 25 42-1 41-7 61 21* 54>"8 62'6