1826.] Philosophical Transactions for 1826, Farts Land II, 65 



An abstract of Capt. Kater's paper now before us, has already 

 appeared in the Annals for February last ; but there are some 

 particulars respecting the construction of the standards, and the 

 adjustment of the national copies of the imperial standard-yard 

 rigorously identical in length with Sir G. Shuckburgh's scale, 

 that demand insertion in this place. 



Brass being peculiarly liable to decomposition in the atmo- 

 sphere of London, the standards of weight and of measure of 

 capacity, have been formed of an alloy, consisting of 576 parts 

 of copper, 59 of tin, and 48 of brass ; and this is equal in hard- 

 ness to hammered brass, and can be worked with the same 

 facility. 



The construction of the standards of measure of capacity, ai?id 

 of the weights, is thus described : 



" In order to avoid any innovation but such as might be 

 absolutely necessary, it was deemed expedient in construct- 

 ing the bushel, to adhere as nearly as possible to the form pf 

 that known by the appellation of the Winchester bushel. It 

 was therefore directed to be made cylindrical, the interior dia- 

 meter being about 18i inches, the exterior 19 J- inches, and the 

 depth about 84. inches, and intended to contain eighty pounds 

 avoirdupois of distilled water. In order to give the bushel addi- 

 tional strength, it was cast with two projecting hoops, one to 

 which the bottom was screwed, and another at the distance of 

 about half an inch from the top. 



*' Considerable difficulties arose in casting the bushel ; out 

 of twelve, only five proved sound enough for use ; but by vary- 

 ing the process, they were at length procured sufficiently per- 

 fect. Much credit is due to Mr. Keir, the engineer employed 

 by Mr. Bate in turning the bushels, for the beauty and perfec- 

 tion of his work. 



" The form of the gallon measure occupied much of my 

 attention. It was necessary that it should be such as to enable 

 me to determine the weight of distilled water it should con- 

 tain with the least liability to error. The conical form was there- 

 fore adopted ; the mouth being made cylindrical, and one 

 and a half inch diameter : the top was ground perfectly flat, 

 and the edge so rounded off", that the contents might be 

 poured from it into any other vessel without running down the 

 side. The cone was placed in a cylinder about four inches 

 high, in which handles were formed, and which served at the 

 same time to protect the gallon from injury, and to prevent 

 any change of temperature which might arise from handhng. 

 The quart and the pint measures were of the same form, on a 

 smaller scale. 



, '* The weights were of brass, and nearly of a spherical 

 form, but flattened at the bottom. Into the top was screwed 

 a button J beneath which a small cavity was left to. receive 



