Uses of a Line-Divider. 285 
the point where it meets AC. Move it on to cB, slide back 
to 4, and mark point d where it meets AC; joindB. dB is 
the line required, as may easily be seen by comparing the 
portions given and taken by the respective fields. This line 
would only divide the fields perfectly accurately as before, if 
A12, 234, &., were rectilineal angles ; butit is the nearest 
approximation possible, and the one always used. 
The divider would also be useful on board ships for drawing 
lines on charts parallel to other lines at some distance. It 
would be much better for this purpose than an ordinary 
parallel ruler on account of its very large range and capability 
of being fixed. 
Of course the line-divider can be used in all cases in which 
parallel rulers are ordinarily used. 
In summing up, the advantages of the line-divider appear 
to be these :— 
1. Lines of division can be drawn at any angle to the line 
to be divided. 
2, Areas can be divided by equidistant lines parallel to any 
given line. 
3. Since the divisions on the instrument are all equal, they 
may conveniently be made inches and parts of an inch; and 
4, consequently the number of divisions may be made as 
great as we like without materially increasing the cost. 
5. Lastly, the cost of the instrument is small, and it is 
made by Messrs. Stanley in three sizes—6, 12, and 24 inches 
in length. 
Phil. Mag. 8. 5. Vol. 19. No. 119. April 1885. Xx 
