52 Kansas Academy of Science. 



A MOST WONDERFUL TOOL. 



By John H. Klopfer, Topeka. 



1"^HE amazing adaptability of the steel square to the solving of 

 a thousand and one problems in mathematics which puzzle the 

 carpenter, will surprise those who know the square only as an in- 

 strument of measuring and squaring of boards and timber, and 

 trying up angles. 



In conjunction with the square it will be necessary to have a 

 good four-fold, two-foot rule, with the duodecimo or twelfth scale 

 marked on one of its outer edges. The outer edge of one side of 

 the steel square, on both the tongue and blade, has each inch di- 

 vided into twelfths. This is the side which will be mostly used, 

 as each inch will represent one foot, and each subdivision one inch, 

 or a scale of one inch to the foot. 



The standard steel square has a blade 24 inches long and 2 

 inches wide, and a tongue 14 to 18 inches long, 1| inches wide. 

 The blade is exactly at right angles with the tongue, and the angle 

 formed by them is an exact right angle or square corner. 



A proper square should have the ordinary division of inches, 

 half-inches, quarters and eighths, and often sixteenths and thirty- 

 seconds. Another portion of the square is divided into twelfths of 

 an inch; this portion is simply a scale of twelve feet to an inch, and 

 is used for any purpose, as measuring scale, drawing, etc. The di- 

 agonal scale on the tongue near the blade, often found on squares, 

 is thus termed from its diagonal lines. However, the proper term 

 is centesimal scale, for the reason that by it a unit may be divided 

 into 100 equal parts, and, therefore, any number to the one-hun- 

 dredth part of a unit may be expressed. 



In this scale A-B is one inch; then, if it be required to take off 

 y^o\ inch, set one foot of the cjmpass in the third parallel, under 

 1 at E, extend the other part to the seventh diagonal in that 

 parallel at G, and the distance between E and G is that required. 

 For E-F is one inch and F-G 73 parts of an inch. Upon one side 

 of the blade of the square running parallel with the length will be 

 found nine lines divided at intervals of one inch into sections or 

 spaces by cross-lines. This is the plank, board and scantling 

 measure. On each side of the cross-lines referred to are figures, 

 sometimes on one side of the cross-line and often spread over the 

 line, thus : 1X4-9/-. We will suppose we have a board twelve 



