FRICTION OF ROPES.

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pressure by any curves in the line of the road,then the friction will amount to one-tliird ofthe whole of that weight, if no rollers wereemployed.—Knowing- the diminution, by thesize of sheeves fixed upon, the actual frictionis found.

Having- thus ascertained the ratio of the fric-tion to the weight, it will be evident that thefriction of ropes of different lengths will be inproportion to those lengths, or to the weight.

The preceding proportion, expressing theresistance of the rope, I trust may be dependedupon as a datum of calculation in general; but,in applying it to practice, it must undergo somelimitation. It has been ascertained, underfavourable circumstances, the planes werenot prepared for the purpose; but taken asin actual use, and as they had remained forsome years; but, during the experiments,the weather was favourable, and this hasconsiderable cft’ect upou the resistance ; wemust, therefore, found our calculations upondata which will hold good under every possi-ble variation of weather, and this can only bedone by appealing to practice.

In the selection of the planes which I havehere given, there is one which I consider justadequate, with the number of carriages usually