April 17, 1908] 



SCIENCE 



617 



From the experiments described it is 

 clear that the effects produced were due to 

 a primary activity possessed by the salt 

 and not due to a secondary activity im- 

 parted to it. 



On Variations in the Penetrating Radia- 

 tion from the Earth: C. S. Weight, 

 University of Toronto. (Communicated 

 by Professor J. C. McLennan.) 

 In this paper the author gives an ac- 

 count of some measurements made on the 

 penetrating radiation from the earth in 

 different localities on the north and south 

 shores of Lake Ontario, and also at differ- 

 ent points on the surface of the lake during 

 the passage over it by steamer. 



In making these measurements observa- 

 tions vs^ere taken by means of an electro- 

 scope of the improved Wilson type on the 

 saturation current through the air in a 

 closed lead cylinder. 



The following statement contains a sum- 

 mary of the results. In this table the 

 conductivities are corrected for variations 

 in temperature and pressure, and are ex- 

 pressed for purposes of comparison by the 

 number of ions generated per c.c. per sec- 

 ond within the cylinder at the different 

 points of observation. 



tabu; of condtjctivities 



No. of ions 

 generated 

 per c.c. per 



second 

 within the 

 lead cyl- 

 Observation Stations inder 



First Set of Observations 



Physical Laboratory, University of To- 

 ronto 22.5 



At edge of harbor waters (30 meters from 

 shore) (filled-in ground) 19.3 



South end of breakwater at Eastern Gap 

 (water 4 meters deep) 14.1 



On sand spit between lake and harbor 



(110 meters from shore) 14.26 



On ground floor Canoe Club, at end of 

 pier in harbor (water under floor 6.5 



meters deep) 13.5 



Second Set of Observations 

 Old Physics Building, University of To- 

 ronto 23 



New Physics Building 22 



On board steamer Corona at doelv 18 



At difi'erent points between Toronto f 18.91 

 Harbor and Niagara River bell buoy I 18.8 

 av. 18.8 I 19.1 f 

 [18.3J 



At Niagara dock 20 



Niagara River, Paradise Grove 18.2 



Queenston Heights 23.3 



Niagara Falls Park 22.9 



Elevator Shaft, Ontario Power Co., Ni- 

 agara Falls (40 meters under ground) 22.6 

 At foot of Niagara Falls 20.3 



A Null-reading Instrument for the Meas- 

 urement of Ionization: S. J. Allen, Uni- 

 versity of Cincinnati. 



A Comparison of the Formulas of Helm- 

 holtz and of Nernst for the E.M.F. of 

 Concentration Cells: H. S. Caehaet, 

 University of Michigan. 



The Stability of Cadmium Cells: H. S. 

 Carhabt, University of Michigan. 



On the Separation of Echelon Spectra by 

 Gratings: A. A. Michelson, University 

 of Chicago. 



Selective Reflection as a Function of the 

 Atomic Weight of the Base: W. W. 

 CoBLENTZ, Bureau of Standards, Wash- 

 ington. (Bead by title.) 



The Infra-red Absorption of Certain 

 Biaxial Crystals for the Three Principal 

 Directions of Vibration: R. E. Nts- 

 WANDEK, Cornell University. 



Neiv Physical Aids to Navigation: H. E. 

 Wetherill, Philadelphia. (Read by 

 title.) 



The Distribution of Energy in the Spec- 

 trum of the Tungsten Filament: R. E. 

 Nyswandee, Cornell University. (Read 

 by title.) 



