130 



SUMMAEY OF CUKRENT RESEARCHES RELATING TO 



Fig. 24. 



required, a narrow strip of blotting-paper can be damped and placed 

 round the central hole, making it adhere to the sides. 



Another form (fig. 24) consists of a hollow ring of brass. If in. 

 external diameter, the tube of the ring being about l-dth in. outside 



diameter. A saw-cut is 

 made almost through 

 the ring, and into it 

 is soldered a partition 

 plate. On each side, 

 about l-4th in. from the 

 partition, two holes are 

 drilled into the tube, and 

 into each is soldered a 

 fine brass tube; at the 

 opposite side of the ring 

 is soldered another tube, 

 closed at the end that 

 is fixed in the ring. Into this, when in use, is placed the end of a 

 small clinical thermometer. Indiarubber tubes are attached to the 

 two brass tubes, as in the former, terminating in glass tubes with 

 small orifices. 



Two flat plates of thin ebonite are also required, with central 

 apertures of the same diameter as in the previous forms, the bottom 

 one having its aperture closed with a stout cover circle, and the upper 

 one with a thin cover circle cemented to the inner surface. 



To use the ring-stage, place a narrow ring of damp blotting-paper 

 on the upper surface of the bottom plate, then a flat ring of india- 

 rubber ; upon this carefully put the brass ring (which has its upper 

 and under surface slightly flattened on the lathe), and on the top, 

 place a similar indiarubber band ; then, having put the material to be 

 examined on the under surface of the thin cover, either protected with 

 mica or otherwise, turn it over upon the indiarubber ring on the brass 

 ring, and bind the two ebonite plates together by two stout indiarubber 

 bands. This is then used in the same way as the former, the tempera- 

 ture obtained being very similar ; the thermometer is placed at any 

 part of the upper plate, but preferably on the part over or between the 

 two brass tubes. 



The brass portion of this form may be put to another use. To a 

 thin ebonite plate with a central aperture (fig. 25) is cemented and 



Fig. 25. 



pinned a circular ebonite block of the same thickness as the ebonite 

 stage of the first form. In the block is turned a central aperture 

 wider at the base than at the top, which is slightly countersunk, and 



