Comparisons of Mercury and Platinum Thermometers. 7 



the Cambridge Scientific Instrument Co., under the super- 

 vision of Mr. E. H. Griffiths. It consists of a coil of fine 

 platinum wire wound on a mica frame whose edges are 

 serrated, to receive the windings. The thick leads running 

 down to this coil are held apart by mica washers, and the 

 whole thermometer is enclosed in a thin glass tube. The 

 thick leads are connected with the terminals marked P P. 



Fig. 1. 



This thermometer was also provided with compensating leads, 

 so that its indications are independent of the depth of stem- 

 immersion, provided this immersion is sufficient to prevent 

 conduction from the outside along the leads to the coil. The 

 compensating leads C C are simply a loop (not connected 

 with the platinum coil) running down the stern parallel to the 

 main leads P P throughout their length, so that they are 



