1885.] .MISS ^fARK■S PATEXT LINE-DIVIDER. 339 



United Service Club, Edinbur^li. Au after appeal will be made to 

 the general public. The Council of the Scottish Arboricultural 

 Society have agreed to recommend their constituents to vote £5(1 

 from the Society's funds for the above object. 



MISS MARK'S PATEXT LIXE-DIVIDER. 



THIS new instrument should interest those of our readers who 

 have occasion to use proportional compasses in plan-drawing. 

 The principle involved in the use of this instrument, for instance, 

 to divide a given length into five equal parts, is that corresponding 

 sides in similar triangles are proportional. 



The instrument, when spread out, A B as shown in the figure, 

 forms a hinged rule with a firm joint ; each limb, in this case, is 

 ten inches in length ; along that of B straight lines can be drawn, as 

 it is bevelled, fronted with brass on its straight edge. On the 

 bevelled edge of the limb A and on its top are divisions of eighty 

 equal parts, so as to admit of dividing a given length into an\- 

 number of equal parts from two to eighty. A, slides in an under- 

 cut groove upon the plain rule C, which has a single line marked 

 iipon it, and is also provided with needle-points on the under side,, 

 to prevent it from slipping when placed in any position. 



In using the instrument to divide a given length into five equat 

 parts, C is slid along A, till its line coincides with one of the line.>- 

 on A, against which is tlie number 50. This line of A is then 

 placed on one end of the line to be divided, and the rule opened 

 out or closed up, till tlie bevel of B passes through the other end 

 of the line. Xow press the points on the under side of C firmly 

 into the paper, and slide A up till the number 4 on the line of 

 reference is coincident with the line on C, and mark the points 

 where the bevel of B meets the given line to be divided. Continue 

 to move A up one division at a time till the whole line is divided. 

 If lines are to be drawn through the several points of division in a 

 given consistent direction, the instrument must be so fixed that the - 

 bevel of B shall be initially in the given direction. 



