DESCRIPTION OF AUTOGRAPHIC STRESS-STRAIN APPARATUS. 253 



Summary of the Number of Species in each class 



Mammalia 



... 9 



Polyzoa ... 



215 



Eeptilia 



1 



Crustacea 



14 



Pisces ... 



... 12 



Annelida .. 



12 



Cephalopoda 



... 3 



Echinodermata .. 



53 



Gastropoda 



... 684 



Zoantharia 



62 



Scaphopoda 



... 9 



Spongida... 



1 



Petropoda 



... 5 



Khizopoda 



165 



Lamellibranchiata 



... 240 









Palliobranchiata 



... 34 





1519 



DESCRIPTION OF THE AUTOGRAPHIC STRESS- 

 STRAIN APPARATUS, 



Used in connection with the Testing Machine at the University of 



Sydney, for recording the results of testing the Strength and 



Elasticity of Materials in Cross-breaking , 



Compression, and Tension, 



By Professor Warren, M. Inst. C.E., Wh. Sc. 



[With Four Plates.] 



[Read before the Royal Society of N.S.W., August 1, 1888.~\ 



The apparatus used for drawing Stress-strain diagrams in Cross- 

 breaking and Compression is illustrated in Plates 1 and 2, and 

 consists of a frame R, which is rectangular in plan, and which is 

 attached to the cross-head of the testing machine in the manner 

 shown on Plate 2. There are two steel axes fixed to the end 

 plates of the frame by means of lock nuts. One axis carries a 

 brass drum 12 inches long by 5 inches in diameter ; the other axis 

 carries a pulley D, fixed upon or cast with a brass pipe E. A 

 spiral groove is cut upon the pipe E, the pitch of which is £ of an 

 inch, there is also a spiral groove cut upon the end of the drum F 

 which is 2 inches pitch. The two spirals are connected by means 

 of a piece of strong catgut, so that for ten revolutions of the 

 spiral E, the drum makes one revolution. The pulley D is made 

 to revolve by means of a steel pianoforte wire wound round its 

 entire circumference and passing upwards over guide pulleys fixed 

 to the ceiling and terminating in a weight of 14 pounds. The 

 wire is led from the pulley D over a guide pulley C, fixed to the 

 frame R and two other guide pulleys R 1 arranged so as to lead 



