1880.] 



J. F. Teunant — On Standard Wei/jhts. 



41 



V. — Account of tlic Verification of some Standard Weiglits tvith consi- 

 derations on Standard Weights in general. — By CoL. J. F. Tennant, 

 II. E., F. II. S., Master of Her Majesty s Mint. 



(Becd. Jan. 5th;— Eead Feb. 4tli, 1880.) 



When I i:rst contemplated the verification of a series of weights from 

 a primary standard, I had little information as to procedure, and indeed 

 I have till now had little as to details. I had intended in this paper to deal 

 with the verification of a whole series of ounce weights ; but circumstances 

 beyond my control have delayed the latter portion, and I think that probably 

 this shorter paper will be as much as the patience of my readers will stand : 

 in it are described, with examples, all the cases I shall meet ; while the ex- 

 planations will, I trust, enable any one to follow my procedure and some- 

 how to verify any other set of weights. This end being gained, the delay 

 of the paper to add the numerical results of farther work, would add little 

 to its popular, or even scientific value, and this circumstance has induced 

 me to offer it in its present state to the Asiatic Society. 



I am aware that I am open to the charge of excessive (factitious) 

 accuracy, and I freely admit that I have used an excessive number of 

 decimal places ; but the number was originally fixed by the fact that it caused 

 no trouble and saved thought. The difference between the trouble of 

 dealing with 5 or 6 figures and 4 with an arithmometer is, in my case, more 

 than compensated by the absence of the absolute necessity of watching 

 the increase of the last figure : and too, I had not, till I had gone some 

 way with these weighings, so clear an idea of the probable errors as I now 

 have. The systematic calculation of these is, so far as I know, new : 

 it has taught me much, and guided me where I might have gone wrong. 

 1 think that it should always be carried out ; but of course, the foundation 

 of the calculation — the estimation of the probable error of one comparison, 

 will not commend itself to all men : — tliose who in other respects may 

 follow my procedure may prefer a diiferent course in this, and, when the 

 system of weighmcnt is different, this datum must be determined in a cor- 

 respondingly different manner. Even then, I hope, that the conclusions 

 I have come to may have their use, for the evidence they offer of the rapid 

 accumulation of error in multiplying from a small primary standard, is quite 

 indeiJcndent of the amount ascribed to the error of one comparison. 



I have added the Tables requisite in reducing the comj^arison of weights 

 of varying density and in determining specific gravity. These are deduced 

 from the same data precisely as those used in the British Standajxls Depart- 

 ment, but I have employed Fahrenheit's thermometer, the English inch, and 

 G 



