. Laboratory exercises in elementary physics. the beam does not rub against the sides of the slot. Increaseddelicacy could be attained by projecting beyond the support oneend of the knife-edge and attaching to it a long pointer readingon a scale upon the lower part of the post. In using these scalesit would probably be best to weigh by substitution, except whenratios only are A form of Post-office balances is shown in Fig. 122. Thebeam A is mounted on the post P, and carries a sliding-weightW. The play of the beam is limited by the stops 88. The scaleon the beam is spaced off by fin
. Laboratory exercises in elementary physics. the beam does not rub against the sides of the slot. Increaseddelicacy could be attained by projecting beyond the support oneend of the knife-edge and attaching to it a long pointer readingon a scale upon the lower part of the post. In using these scalesit would probably be best to weigh by substitution, except whenratios only are A form of Post-office balances is shown in Fig. 122. Thebeam A is mounted on the post P, and carries a sliding-weightW. The play of the beam is limited by the stops 88. The scaleon the beam is spaced off by finding, by trial with various CONSTRUCTION OF APPARATUS. 241 weights, the average space corresponding to the unit of weightused. These spaces with subdivisions are then laid off on thebeam. This device, mounted on a box, would be very good forspecific-gravity work. The capacity coiild be varied by using sev-eral weights which were multiples, etc. A contrivance for deter-mining small weights is shown in Fig. 123. A block of wood, B,is attached to a base-board. A piece of glass rod, G, is drawnout at one end and fastened to B. The end carries a light scale-pan, and the deflections caused by various weights may be readon the scale 8. The deflections caused by known weights arefound by trial, and the scale spaced off accordingly. This instru-ment may be made very sensitive, though its
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Keywords: ., bookcentury1800, bookdecade1890, bookpublishe, booksubjectphysics
