Astronomical and Nautical Collections. 357 



iii. Copy of a Report to the Board of Customs, containing a de- 

 scription of an improved Sliding Rule for gauging Casks. 



Sir, 



In the Report which I ad Iressed to you a few months since, 

 stating my opinion of Mr. Watts's proposals for the improvement 

 of gauging, I promised to send some further observations for the 

 consideration of the Board of Customs, as soon as the legislature 

 should have come to a decision respecting the alterations which 

 have been proposed in the system of weights and measures ; and 

 though it seems that the wine gallon must remain for the present 

 in use, yet as there is every reason to imagine that an imperial gal- 

 lon, exactly one fifth larger, will ultimately be adopted, it might 

 be right to suspend the introduction of any new instruments into 

 general use, until the proposed regulations shall have been more 

 fully appreciated by the House of Lords, and to ascertain in the 

 mean time how far the instrument, which I have the honour to pre- 

 sent to the Board, is likely to fulfil the purposes for which I have 

 constructed it, that is, for determining, upon principles which are 

 entirely new, and with the greatest possible simplicity and expe- 

 dition, the approximate content of any cask whatever, subject to 

 any further corrections which either theory or experience may 

 dictate in particular cases. 



My sliding rule contains four graduated lines, marked, bung 



DIAMETER IN INCHES AND TENTHS, HEAD DIAMETER, LENGTH, 



and CONTENT IN gallons. 



The computation is performed by merely bringing the head di- 

 ameter of the given cask to the bung, on the respective lines ; the 

 content may then be read off opposite to the length of the cask. 



The degree of accuracy of the result may be inferred from the 

 contents of twenty-one casks, as very carefully determined by 

 Mr. Watts, at my suggestion, and by order of the Board. 



No. Bung Head 



I. 30.0 21.8 



II. 28.6 21.7 



III. 31.7 22.9 



