634 



SUMMAEY OF CUKEENT EESEAECHES EELATING TO 



through the conical openings E, and escape through ten flues S, whose 

 orifices can be closed or not at pleasure. The inner tube is closed at 

 the top with a cone into which is fitted a thermometer. Inspection of 

 the interior is by the metal tube r, which bas two glass plates with 

 parallel faces at p. The rotation axis and micrometer movement are 



Fig. ]6'2. 



shielded from the influence of the lieat by a constant stream of water 

 through the iron troughs Q and W'(fig. 161). A metal shield B pro- 

 tects the telescope. The whole copper jacket is wrapped in asbestos 

 cloth. 



For the convenient raising and lowering of the copper jacket, it is. 

 suspended on pulleys fastened to the ceiling of the room and counter- 



