LIME AND CEMENT INDUSTRIES 721 



which carries the axle of the hammer, and keyed to this crosshead 

 and to the cap, so that it may be readily replaced if worn. The 

 steel hammer, weighing 4-J pounds, is similarly fastened to the 

 cap. As soon as the intended number of blows has been delivered, 

 the mechanism is automatically checked, the machine having been 

 so adjusted before the beginning of the work. 



The number of blows required in the standard German tests is 

 150. The forms to receive the mortar consist of a lower and up- 

 per case held together by springs. The lower case for compres- 

 sion specimens consists of two angle irons held on a plane plate 

 by a grinding strip and a screw acting on the latter. Upward 

 motion is prevented by two wedge-shaped surfaces. The lower 

 case and half the upper ones are filled with the mortar to be tested, 

 and a plate laid on its surface. On this plate the blows are deliv- 

 ered. It is of vital importance that the apparatus should rest on 

 a firm non-elastic base. 



The Jameson machine 1 is described by the author as follows: 



The main portion of the machine consists of a cylinder, which 

 is flanged at the lower end, this flange corresponding in size and 

 shape to the upper part of the base. The cylinder is bolted 

 to the base by four bolts, each bolt provided with a filler that 

 holds the lower face of the filler 1 inch above the base plate. 

 Both of these faces are accurately planed. It is between the 

 two plane faces that the molding plate swings, the fillers on 

 the bolts acting as stops. The bore in the cylinder is the shape 

 and size of the briquet. In the bore there works a solid plunger, 

 and the length is suificient to cover the feed hole when at its low- 

 est points. This plunger is operated by a lever. At either side 

 of the plate are two extractors which correspond in outline and 

 size to the opening in the plate, and which are raised by means of 

 levers thus forcing the molded briquet from the plate. 



A high capacity is claimed for this machine, it being stated that 

 three students have made 3000 briquets in 10 hours. 



1 Jameson. Portland cement, p. 50. 



