L. MECHANICS AND ENGINEERING. 483 



The "Richards indicator" and the "Ashton & Story in- 

 dicator" are two instruments specially examined by Berndt; 

 and in these the expansion and contraction of free springs, 

 at ordinary temperatures, are employed as the means of 

 measuring the pressure of the steam a very marked supe- 

 riority being manifested by the latter instrument, so long as 

 the spring is not warmed in consequence of the work that it 

 is called upon to perform. Even when so warmed, it seems 

 to have a decided advantage over the Richards indicator. 

 Programme Inch School at Chemnitz, 1874. 



THE THIRTY-FIVE-TON STEAM-HAMMER. 



The great steam-hammer lately built for the Royal Gun 

 Factories at Woolwich has been successfully erected and 

 set to work. Being much the largest piece of mechanism of 

 its kind in the world, considerable interest attaches to its 

 performance. The weight of the falling portion is nearly 40 

 tons, and its force of impact is greatly augmented by the 

 use of steam to drive it down from the top, the augmentation 

 being estimated to equal the force represented by allowing 

 the hammer to fall, of its own weight, from a height of 80 

 feet. It has been allowed a striking fall of 15 feet 3 inches. 

 The hammer is 45 feet high, and covers, with its supports, a 

 base of about 120 square feet. Its weight is about 500 tons 

 above the ground, and the iron used in the foundation below 

 weighs 665 tons. 



THE USE OF AMSLER'S PLAXIMETER. 



The well-known planimeter of Amsler, that has during the 

 past ten years taken so prominent a position as an accurate 

 assistant in all engineering calculations, has had a new use 

 suggested by Kopcke, who, at a recent meeting of the Asso- 

 ciation of Engineers and Architects, at Leipsic, explained how 

 the planimeter may be employed for the determination of the 

 cubic contents of embankments, excavations, and other sim- 

 ilar problems. If to this new use we add the application 

 suggested by Professor Frankel, to the determination of the 

 weight and strength of trestles and beams, it becomes evident 

 that the planimeter is destined to occupy a still more im- 

 portant place in the engineer's office. Protokolle Sdclts. In- 

 (jenieur Verein, 1873, 3. 



