Sinopsis
This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1901 Excerpt: ... wire, standard wire gauge S. W.G. No. 18, cutting pliers, fine file. Method.--Straighten very carefully a portion of the wire, and measure and cut off exactly 10 cms. of it. Weigh this 10 cms. of wire to within 0.01 grammes. Its mass will be found to be about 0.91 gramme. Hence each cm. of the wire will have a mass of something like 0.095 gramme. 0.5 Therefore, to get 0.5 gramme of it we shall need =5-3 (cms.) almost. Now cut off as exactly as possible 5.4 cms. of the wire. Place the 0.5 gramme weight in the right-hand pan and counterpoise it exactly with pieces of tinfoil placed in the other. Remove the weight and replace it by the piece of brass wire. It will be found that this outweighs the counterpoise, and if it does not it has been taken too short, and a fresh piece must be cut off. It should, however, only just outbalance the tinfoil, or the work ofadjusting it will be very tedious. Having now obtained a piece of wire with a slightly greater mass than the weight we wish to copy, we have next to mark the value it is to have. This can be done by making a series of bends in it and letting each "arm" stand for one "unit" (in this case of course the "unit" is 1.0 gramme). Our piece of wire will therefore be bent into a pentagon, one of the free ends being turned up for convenience in lifting. It only remains to make the final adjustment of the mass of the bent wire. This is done by rubbing one end of it upon the fine file and from time to time replacing it in the pan until it is found exactly to balance the counterpoise. It has then evidently the same mass as the weight it replaces. If it be desired to reproduce any of the other weights the following hints will be found useful:--For weights 5 grammes to 1 gramme, brass wire ...
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Reseña del editor
This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1901 Excerpt: ... wire, standard wire gauge S. W.G. No. 18, cutting pliers, fine file. Method.--Straighten very carefully a portion of the wire, and measure and cut off exactly 10 cms. of it. Weigh this 10 cms. of wire to within 0.01 grammes. Its mass will be found to be about 0.91 gramme. Hence each cm. of the wire will have a mass of something like 0.095 gramme. 0.5 Therefore, to get 0.5 gramme of it we shall need =5-3 (cms.) almost. Now cut off as exactly as possible 5.4 cms. of the wire. Place the 0.5 gramme weight in the right-hand pan and counterpoise it exactly with pieces of tinfoil placed in the other. Remove the weight and replace it by the piece of brass wire. It will be found that this outweighs the counterpoise, and if it does not it has been taken too short, and a fresh piece must be cut off. It should, however, only just outbalance the tinfoil, or the work ofadjusting it will be very tedious. Having now obtained a piece of wire with a slightly greater mass than the weight we wish to copy, we have next to mark the value it is to have. This can be done by making a series of bends in it and letting each "arm" stand for one "unit" (in this case of course the "unit" is 1.0 gramme). Our piece of wire will therefore be bent into a pentagon, one of the free ends being turned up for convenience in lifting. It only remains to make the final adjustment of the mass of the bent wire. This is done by rubbing one end of it upon the fine file and from time to time replacing it in the pan until it is found exactly to balance the counterpoise. It has then evidently the same mass as the weight it replaces. If it be desired to reproduce any of the other weights the following hints will be found useful:--For weights 5 grammes to 1 gramme, brass wire ...
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