BAIRD &.TXTLOCK: (LONDON) LTD. 



3208 



3209 



3208 s Faber's Calculating Rule, for students, n in. long, with decimals and ordinary cursor, 



with book of instructions . . . . . . . . . . . . each 050 



3209 s Faber's Calculating Rule, for the pocket, 5| in. long, without decimals and with ordinary 



cursor, with book of instructions . . . . . . . . . . each 050 





il 



3210 



3210 s Faber's Improved Calculating Rule, loj in. long 



The cursor consists of a wooden frame with wire line, and travels in a groove along the upper edge of the rule 

 The rule is provided with projecting pins at either end, which rest in two hooks fixed in the wall, so that 

 results may be read successively on both front and back without difficulty, all that is needed, in order to display the 

 markings on the back, being to turn the rule up. The cursor is easily moved backward and forward. 

 It is made of seasoned wood, painted white, with black scale and black figures. 



086 



Reduced size. 

 3211 



Sectional view, full size 

 3211 



3211 s Improved Calculating Rule, n in. long, with digit registering cursor 



The value of this instrument to engineers, architects, and technical men generally is obvious, and is fully 

 demonstrated by the continually growing demand. 



The rule is made either entirely of boxwood or with celluloid surface, the latter being usually preferred on 

 account of the greater clearness of the markings. 



The rule has one side bevelled, the other being at right angles, as illustrated, the moderate size of the instru- 

 ment, which is loj in. long, together with the neat case in which each is sent out, rendering it specially adapted 

 for pocket use and outdoor purposes. 



The set of scales on the reverse of the slide, for solving trigonometrical problems and logarithms, considerably 

 enhances the value and usefulness of the rule. 



10 6 



CROSS STREET HATTOIST GARDETST, E-C 



608 



