abstracts: spectroscopy 399 



nite extent of the atmosphere, the magnetic effects which result as the 

 ultimate consequence of a feeble source of ionization may be very much 

 greater than those calculated on the basis of a shell of finite thickness. 



W. F. G. S. 



PHYSICS. — Protected thermoelements. Arthur W. Gray. Bureau 

 of Standards Scientific Paper No. 276. Pp. 3. 1916. 



The mounting described in this paper has been found to be very 

 convenient for protecting laboratory thermoelements from damage 

 by contamination or by mechanical strains. 



The closed tube which covers the temperature determining end of 

 the thermoelement has its open end cemented into one end of a flexible 

 copper tube, through which the wires, properly insulated, pass to a 

 head at the other end. Projecting downwards, from this head is a 

 glass tube which contains the ice junction. The head is provided 

 with neutral binding posts for receiving the leads to the apparatus 

 employed for measuring the electromotive-force by which the tem- 

 perature is determined, and contains phosphorus pentoxide to prevent 

 moisture films from being deposited within the protective covering. 



The ice-bath is contained in a vacuum jar which is protected by a 

 metal case. By means of a bayonet joint this is suspended from 

 the cover, which is fastened to a rod fitting the standard laboratory 

 clamps. The head of the thermoelement telescopes with moderate 

 friction into a split tube which projects upward from the top of the ice- 

 bottle cover. When it becomes necessary to renew the ice, a slight turn 

 of the case containing the vacuum jar frees the bayonet joint and per- 

 mits lowering of the ice-bath without disturbing anything else. 



A. W. G. 



SPECTROSCOPY. — Interference measurements of wave lengths in the 

 iron spectrum (3233A-6750A). Keivin Burns, W. F. Meggers, 

 and Paul W. Merrill. Bureau of Standards Scientific Paper No. 

 274, pp. 245-272. 1916. 

 The wave lengths of 403 iron lines have been measured by means of 

 interferometers in an effort to determine standards at intervals of 

 about 10 angstroms. This has been accomplished in the greater part 

 of the spectrum between 3233A and 6750A, the region in which the In- 

 ternational secondary standards exist. As far as possible, lines of all 

 intensities were measured. 



