INDUSTRIAL PROGKESS DURING THE YEAR 187G. xlvii 



steel rod 6 mm. in diameter, over the lower end of which is passed a 

 tube of vulcanite 25 mm. in diameter and 165 mm. long, secured by 

 an adjusting screw at the lower end of the pendulum rod. A brass 

 bob 63 mm. in diameter and 156 mm. long slides over this vulcanite 

 tube, and rests upon its top. The upward exjjansion of the vulca- 

 nite should be equal to that of the steel rod and the bob downward. 

 The coefficient of exjDansion for 1 Centigrade of the vulcanite was 

 0.000079365. 



Cailletet, who has been working upon the problem of chemical 

 action under high pressures, has contrived a simple form of pressure 

 gauge, founded on the compressibility of glass. By experiment he 

 proved that a cylindrical glass reservoir suffers, when compressed, a 

 diminution of volume exactly proportional to the pressure exerted. 

 The new manometer consists, therefore, of a large glass thermometer, 

 with a cylindrical bulb containing either a colored liquid or mercu- 

 ry, and inclosed in a cavity in a steel reservoir, communicating by 

 a brass tube with the apparatus in which the pressure is to be meas- 

 ured. To maintain the temperature constant, the whole apparatus 

 is f)laced in melting ice during use. The indications are reliable. 



Parish has described a simple form of balance for taking specific 

 gravities of solids, constructed somewhat like a common form of 

 letter scale, with unequal arms, the substance being placed in a pan 

 (which can be immersed in water) at the end of the shorter arm, 

 while the longer is graduated directly to give the specific gravity. 



Schott has examined the character of the crystallizations which 

 are produced in common glass under various conditions, with a view 

 to elucidate the chemical character of glass itself. 



Nipher has published a paper on the variation in the strength of 

 a muscle, in which he calls attention to the fact that after the rela- 

 tion of the strength of a muscle to the dynamical work of exhaustion 

 has been determined, its strength at any time is easily found by 

 measuring the dynamical work of exhaustion. He also finds that 

 the coefficient of power of a muscle per square centimeter of its 

 section is very variable ; so that the work a muscle can do depends 

 not alone upon its size, but also upon its quality. 



Victor Meyer has devised a simple and very efiective method of 

 determining the solubility of salts in solvents, Avhich is rapid and 

 accurate, whatever be the temperature at which the solubility is 

 taken. 



Meunier has observed a quartzose sandstone from the vicinity of 

 Orsay, Department of Seine-et-Oise, France, perforated through and 

 through by the roots of trees. The grains of quartz are held togeth- 

 er by a calcareous cement, which is the material upon which the 

 carbonic gas exhaled by the roots has exerted its solvent action. 

 These roots were those of the elm, and were of all sizes, from a cen- 

 timeter and more to less than a millimeter in diameter. The author 



