S* Mr. C. Holtzapffel on a Scale of Geometrical Equivalent 



of the whole series may be observed at one view, by the as- 

 sistance of a particular kind of square represented in the 

 wood-cut. It consists of two slips of card, connected at the 

 upper and lower edges by two slips of wood glued between 

 them, so as to make a kind of slider or ferrule. 



The first idea was to cut the edge of the card square; but 

 a better mode subsequently suggested itself, namely, to draw 

 a line across the index, and then to serrate the edge, so that 

 the several parts of the line might serve for the more accurate 

 appreciation and subdivision of the graduations by the eye. 

 At the same time, the card index receives the titles of the 

 scales A, B, C, &c. and there is therefore no necessity to dis- 

 tress the eye by running continually to the end of the instru- 

 ment to ascertain the same, as the index gives all the parti- 

 culars called for, in immediate contiguity. 



The 20 lines of graduations selected for one side of the 

 present instrument are arranged as follows : 



A. Cubic yards 



B. Cubic feet 

 , C. Cubic inches 



D. Spherical inches 



:> Cubic measures. 



E. Superficial yards 



F. Superficial feet 



G. Superficial inches 

 H. Circular inches 



I. Imperial gallons 

 J. Bushels 

 K. Barrels 

 L. Tuns 



M. Pounds troy 



N. Pounds avoirdupois 



O. Cwts. 



P. Tuns 



T Areas and columns, 

 one foot high 

 or deep. 





Measures of 

 capacity. 



Weights estimated 

 in water. 



Q. French lineal metres "^ 



R. French cubic metres I French metrical 



S. French super^ metres [ system. 



T. French kilogrammes. J 

 All these scales are graduated to one common standard, 

 namely, the unit described in the pamphlet*, one tenth of an 

 inch English representing one cubic foot English : all the 

 others are multiples and submultiples, proportionate to the 

 values of the several measures. 



* P. 31. 



