592 



Mr. H. Redmayne Nettleton on a New 



The form eventually adopted consists of two specially cast 

 iron reservoirs R x R 2 (fig- 2) about 40 cms. long and of 5 cms. 



Fig. 2. 



internal diameter, to which by strong rubber tubing bound 

 by wire the glass tube T was attached. This latter a little 

 less than 3 cms. in diameter and 40 cms. long — its ends 

 being bent as shown — had five side limbs through which 

 thermometers t 1 ^t 5 were inserted and fastened in with 

 cement. The thermometers had cylindrical bulbs of small 

 radius and were about 6 cms. apart. 



Two limbs Lj L 2 were attached to the iron reservoirs and 

 these latter were surrounded with tin-jackets J l J 2 . Screws 

 Si and S 2 were provided so as to allow the air to escape in 

 filling the apparatus, these screws being inserted with the 

 aid of cement as soon as the mercury reached the top of 

 the reservoirs. 



A capillary tube C was attached to the top of the limb L,, 

 and to L 2 pressure tubing was attached leading to a vessel in 

 which the head of mercury was kept constant by an ove?*- 

 flow pipe. By raising or lowering this vessel the head could 

 be varied and a constant outflow of mercury from the capil- 

 lary C could be obtained. 



A spiral SC of flexible tin tubing leaving the steam jacket 

 J\ was found useful for keeping up the temperature, thus 

 enabling a larger temperature-slope to be investigated ; for 



