584 SUMMARY OF CURRENT RESEARCHES RELATING TO 
completely closed, but a continual stream of water passes through the 
apparatus with a varying rate of flow. 
The dimensions of the apparatus are such that for a range of tem- 
perature from + 20° C. to + 60° C. the displacement of the piston 
amounts to 25 mm. For a very exact adjustment of temperature many 
slight movements of the tube are necessary. An adjusting arrangement 
Fig. S7. 
S 
is therefore brought on the tube d, on the division of which, displace- 
ments of 0*025 mm. can be read directly. This adjusting arrangement 
is seen in fig. 88. . _ . 
By loosening the clamping screw s ' , the tube d is freely movable in 
the metal piece r, which has a screw thread on its exterior in which the 
corresponding screw of the divided head i engages. The projecting 
Fig. 88. 
ring f fits over a corresponding ring on the piece v which canies the 
screw s' for clamping the tube d. Between v and v is a spiral spring w 
which presses v forwards when the divided head i is turned. The tube y 
is a prolongation of r , and the tube a a prolongation of v. These two 
tubes are connected together by the small screw z. By means of the 
clamping screw s', d is rigidly connected with v and shares in the move- 
