314 JOURNAL OF THE WASHINGTON ACADEMY OF SCIENCES VOL. 11, NO. 13 



Thermometer bridge terminals of thin copper. (4) Smaller and neater 

 thermometer heads. (5) Sealing of the strain-free type of thermometer. 

 (6) Elimination of the drying head on calorimeter thermometers. (7) A 

 method of electrical annealing which seems to effectively relieve all winding 

 strains in the thermometer coil. The subject matter of the paper is given 

 in full in Bureau of Standards Scientific Paper No. 407. 



The paper was discussed by Dr. W. P. White. 



R. H. Wilhelm and Amelia K. Benson : A comparison of the International 

 Hydrogen Scale with the standard scale of temperature defined by the platinum 

 resistance thermometer . (Illustrated; presented by Miss Benson.) 



The International Scale of Temperature adopted by the International 

 Committee on Weights and Measures in 1SS7 is the scale of the hydrogen 

 thermometer set up by Chappuis at the International Bureau, the pressure of 

 hydrogen at 0° C. being one meter of mercury. Chappuis calibrated four 

 verre dur thermometers so as to define the mercury-in-glass scale, and com- 

 pared these thermometers with his hydrogen thermometer to get the cor- 

 rection necessary to convert the verre dur scale to the hydrogen scale. Since 

 the platinum resistance thermometer has proved to be a more reliable primary- 

 standard than the verre dur thermometer, it was decided to compare all the 

 verre dur primary standards of the Bureau with platinum thermometers, 

 and then place the verre dur thermometers in the vault. 



The two scales have been compared by Griffiths in 1893, Waidner and 

 Mallory in 1899, Harker and Chappuis in 1900, and the Bureau of Standards 

 in 1917 and 1920. All the comparisons indicate that the hydrogen scale is 

 lower than the standard platinum scale by perhaps 0.010 degree in the range 

 10° to 30° C. 



The paper was discussed by Messrs. Burgess, Fenner, Harper, Sosman, 

 Millar, Sligh, and Dickinson. The President announced that Miss 

 Benson had the distinction of being the first woman who had ever addressed 

 the Society. 



C. O. Fairchild: New methods of sealing optical glass. (Illustrated.) 



A new process for joining optical glass has been developed which enables 

 one to join glass parts with finished surfaces without distorting the surfaces 

 except at an edge. It has been applied to the construction of colorimeter 

 tubes, cells, etc., polarimeter tubes, incandescent lamps with optical glass 

 windows, haemacytometers, and Nessler tubes, and the protection of surfaces 

 for internal reflection. 



The method is carried out by heating the glass parts while in approximate 

 contact, in an electric furnace, to a temperature at or near the annealing 

 range, and applying heat locally (usually at an edge) by means of a small 

 oxy-gas flame. The progress of joining is viewed through a window in the 

 furnace. 



The process was developed through consideration of the low thermal 

 conductivity of glass, and the rapid change in mobility near annealing temper- 

 atures. These properties make it possible to start fusion by local heating 

 without propagating stress beyond a very restricted portion of the glass. 



It has been found that two polished surfaces nearly in contact will join 

 readily when junction is once started and it is possible to obtain excellent 

 results without polishing the surfaces. A fine ground surface provides a 

 good joint and the fusion is accomplished with almost complete disappearance 

 of the ground part. 



