. Hardware merchandising 1895 . hat required for thecut nail, and that for pulling is considerablymore. 7. The relative efficiency which ishere considered as the ratio of the work ofpulling to that of driving is much higher forthe wire nail than for the cut nail. In making experiments it was noticedthat the cut nail bruised and broke the fibresof the wood, principally at the end of thenail, whereas the wire nail simply crowdedthem apart, and probably did not move themmuch beyond the point from which theywould return by elastic force, and hence thenail would be grasped much stronger perunit of
. Hardware merchandising 1895 . hat required for thecut nail, and that for pulling is considerablymore. 7. The relative efficiency which ishere considered as the ratio of the work ofpulling to that of driving is much higher forthe wire nail than for the cut nail. In making experiments it was noticedthat the cut nail bruised and broke the fibresof the wood, principally at the end of thenail, whereas the wire nail simply crowdedthem apart, and probably did not move themmuch beyond the point from which theywould return by elastic force, and hence thenail would be grasped much stronger perunit of area of surface by the wood. Pre-senting less surface there would be, how-ever, less resistance to starting. To see what the effect of change of formwould be, a number of tenpenny cut nailswere sharpened on the point by grinding toan angle of about 30 degrees, so that thefibres in advance of the nail would be thrustaside, and not bruised and broken. This Summary of Experiments in Driving and Pulling Nails in Southern Pine each X inch. Diagrams were then drawncorresponding to the force exerted and thedepth of penetration, the integration of thesediagrams giving the total work either fotdriving or for drawing. Experiments weremade on ten nails of each kind, and theaverages taken to represent the work of anyparticular class. The general summary of the experi-ments is given in the following table, fromwhich it will be noted : 1. That very muchmore force is required to drive a cut nail agiven distance than a wire nail. 2. Thatmore force is required to start a cut nailgenerally than to drive it, and that it invari-ably starts much harder than a wire The work in inch-pounds per nail re-quired in driving cut nails is much morethan that in driving wire nails. 4. Thework in inch-pounds in pulling cut nails isabout equal, sometimes less and sometimesgreater, per nail, than that tor pulling wirenails. 5. The maximum force per pound indriving or starting wire nails is more ne
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