I. SLIDE KULES. 3 



The lines on the rule are the A, B, C, D, MD, (or malt depth) 6x or variety 

 lines, viz., 1st, 2nd, 3rd, 4th, Dr. Button's and Dr. Young's, and two ullage 

 lines (segment standing and segment lying). 



The A, B, C, and D lines are commonly called Gunter's lines (from Gunter, 

 the celebrated mathematician, who was the first to apply a logarithmic line 

 to the instrument for the solution of arithmetical problems) of which the A, 

 B, and C, are merely repetitions of each, and laid down to single radius, and 

 the D to double radius. 



The MD line is similar to the A, B, and C, but is a broken line of two radii, 

 with the figures and divisions in an inverted order (reading from right to left), 

 commencing at 2218 192 in the right-hand radius, and ending at the same 

 point in the left-hand radius, 2218- 192 being the number of inches in a 

 bushel. By the method in which this line is arranged and used in conjunction 

 with the A, B, and C lines the contents in bushels of rectangular and similar 

 figures may be found at one operation. 



The X or variety lines or lines of special gauge points (invented by Mr. 

 Woolgar) for finding the mean diameter of a cask whatever its form ; these 

 lines commence at 18 789, the circular gauge point, and are extended accord- 

 ing to each variety to which they may be applied. 



The ullage lines are rules for finding the contents of a cask by comparison 

 with a standard cask holding 100 gallons, a form nearest those frequently 

 occurring in practice. 



It cannot be ascertained by whom these lines were invented. 



The fixed gauge points on the rule are those for the imperial gallon and 

 bushel, both square and round. 



These rules are principally used by excise officers and maltsters. So ad- 

 mirable is the arrangement, that nearly every problem to which the principle 

 of the slide rule is applicable can be solved on one of these rules. 







lie. Slide Rule, invented by Mr. Coulson, of Redan, used 

 for setting out railway curves, finding the weights of materials 

 from their specific gravities, breaking strains, &c. 



Dring and Page. 



The applications of this rule are so varied that the author's description of 

 them exceeds 400 octavo pages of closely printed matter. 



12. Slide Rule, by M. Mabire. 



Conservatoire des Arts et Metiers, Paris. 



12a. Cylindrical Beckoning Rule. (The property of the 

 Conservatoire des Arts et Metiers.) 



M. Mannheim, Professor at the Polytechnic School, Paris. 



13. Calculating Rules, 1 of 50 cm., 1 of 36 cm., 1 of 26 

 cm., as arranged by M. Mannheim. 



M. Tavernier Gravet, Paris. 



13a. Small Cylindrical Calculating Machine. Arranged 

 by M. Mannheim. Conservatoire des Arts et Metiers, Paris. 



14. Pocket Calculator, arranged by Major-General A. De 

 Lisle, R.E., for the use of engineers. ' Elliott Brothers. 



A 2 



