Economy of Machinery and Manufactures. 109 



In later times, also, sound has been employed to enable men to unite 

 their efforts at a given point. " In removing the vast mass of granite, 

 weighing above twenty eight thousand pounds, on which the eques- 

 trian staute of Peter the Great is placed, at St. Petersburgh, a 

 drummer was stationed on its summit to give the signal for the united 

 efforts of the workmen." 



" The economy of human time" is an advantage, second only to "the 

 addition to human power " which machinery gives to manufacturers. 



The use of gunpowder in blasting rocks, and of the diamond in 

 cutting glass, offers familiar examples of the economy of time. In 

 the former, effects are produced in a short space of time, which could 

 not be accomplished, even with the best tools, in many months. 



An important improvement has been made in the art of using the di- 

 amond, which twenty years since, even after seven years' apprentice- 

 ship, many glaziers were but indifferently skilled in. " This arose 

 from the difficulty of finding the precise angle at which the diamond 

 cuts, and of guiding it at the proper angle, when found." In the im- 

 proved tool, the gem is set in a small piece of squared brass, with its 

 edge nearly parallel to one side of the square. A person, skilled in 

 its use, files away one side of the brass until, by trial, he finds that 

 the diamond will make a clean cut, when guided by keeping this 

 edge against the ruler. Thus the merest tyro, at once applies the 

 cutting edge at the proper angle.* 



"The relative hardness of the diamond indifferent directions is a singular fact. 

 An experienced workman ground one on a cast iron mill with diamond powder for 

 three hours, without its being at all worn, but on changing its direction with refer- 

 ence to the grinding surface, the same edge was quickly ground down." 



i ■ ■ 



3rd. The. advantage of machinery and manufacturing is, most 

 strikingly, obvious, in the saving of materials, apparently worthless. 

 Nothing can seem of less value than the worn out remnants of tin 

 ware, the offals of animals and the sweepings of workshops, and yet 

 such is the result of economy and science, that nothing is lost, but 

 the products of little intrinsic value are made valuable by the skill of 

 the manufacturer. 



» 



"Gold-beater's skins are made of animal offal. The hoofs and horny refuse of cattle are 

 employed in the production of prussiate of potash, that beautiful yellow crystallized 

 «alt, which is exhibited in the shops of chemists. The worn out sauce pans, tin ware, 

 and coal scuttles, when beyond the reach of the tinker's art, have not completed 

 their useful course. Their less corroded parts are cut into strips, punched with 



* See page 9, Economy of Machinery and Manufactures. 



