218

FRICTION OF ROPES.

employed, to effect a regular and constantpassage during all states of the weather, (ex-cept under very extraordinary circumstancesindeed, such as the rails being covered withsnow ;) I shall, therefore, make that the foun-dation of my data for estimating the effects onother planes. — To effect the descent of anycarriage or train of carriages down a plane bythe action of gravity, we must give a certainexcess of preponderance above the friction ofthe respective parts, to accomplish that descentin a given time ; and this time will be entirelygoverned,‘and be in precise proportion to theexcess of gravitating force employed, comparedwith the weight of the carriages,

AVS

being as W l —~rt~

The self-acting plane, Experiment XIV., isone which, when six loaded carriages are em-ployed in dragging six empty carriages up bythe rope there described, I can safely state,from a daily opportunity of witnessing its action,has just sufficient preponderancy to effect therccpiired effect, and I do not think it would beproper in any case to allow less.

The whole weight there moved = W + m will be 69384 lbs.,and the excess of preponderance above the friction and re-sistance of the whole train G — g + F + f+ p will be equalto 400lbs. nearly.