ART. 9. HISTORY OF INVENTIONS HOUGH. 17 



not exceed an inch or two in diameter, these were ample for their 

 needs. The Eskimos made their harpoon heads of hard serpentine 

 and jadeite and by means of sand and shite were able to sever blocks 

 of these stones 8 inches wide and 2 inches thick. The discovery of 

 copper greatly added to the effectiveness of the implement, this 

 metal being an excellent carrier of sand. The use of steel and of 

 diamond edges and the perfecting of the teeth bring the saw to its 

 latest effective forms. 

 No. 1. Flake, with rough edges, one portion better fitted for tlie hand- 100,591 



No. 2. Flakes specially made for saws, chipped 100,471, 173,568 



No. 3. Spearhead specially modified for saw 171,454 



No. 4. Flint saw, one edge specially chipped, the other curved to fit in a 



handle 100,965 



No. 5. Sand saw ; cutting done by means of wet or dry sand carried by wood 



or soft stone 13,120 



No. 6. Saw of soft metal to carry emery, corundum, or hard cutting material, 



55,945 

 No. 7. Steel saw blade with irreg-ular teeth ; handle variously attached— 2.318 



No. S. Steel saw ; serrate teeth ; with or without backing 120,501 



No. 9. Steel saw with serrate teeth ; set 128,154 



No. 10. Japanese saw with reversed teeth 128,151 



No. 11. Modern panel saw of steel ; skewback ; handle of wood to fit the hand ; 



teeth set. Gift of Henry Disston and Sons. 

 No. 12. Crosscut saw for one man, with separate handles for each hand ; 



teeth dentate, not set. (Model.) Gift of Henry Disston and Sons. 

 No. 13. Crosscut saw for two men ; teeth dentate ; back and front curved out- 

 ward. (Model.) Gift of Henry Disston and Sons. 

 No. 14. Circular saw and band saw. Both have serrate teeth and are designed 

 to have continuous motion, the one revolving on an axle, the other 

 working over two drums. Gift of Henry Disston and Sons. 

 No. 15. Sections of crosscut saws: (1) teeth, three-fourths of an inch apart; 

 (2) Humboldt pattern, with two cutting and. one double-pointed 

 scraping teeth; (3) "fleam tooth" with double cutting points, per- 

 forated. Gift of Henry Disston and Sons. 



SERIES 3. — DKILL. 



Plate IS. 



A drill is a tool for making a hole. When acting in soft materials 

 it plays the part of an awl or needle and is then moved by pressure. 

 In hard substances drills of a class acted upon by hammers give rise 

 to tools called punches. Drills of a third class, shown in this ex- 

 hibit, act through circular friction, either by continuous or by recip- 

 rocating motion. This class becomes, according to the actions and 

 sizes and the nature of their working parts, brad awls, gimlets, drills, 

 augers, and so on. The most primitive form of the drill is a natural 

 object with a hard point. Among savage peoples drills of hard stone 

 are made by flaking one portion to a point and leaving the other for 

 a hand hold. Stone drill points are followed by those of metal, Avhich 



