A 



Prob. 



Error. 



5-45 







49—5-58 







5'67 







56 5-50 







Chemistry and Physics. 503 



7. The Doctrine of Energy ; a Theory of Reality. By B. L. L. 

 12mo, pp. x, 108. London, 1898 (Kegan Paul, Trench, Trtlbner 

 ■& Co.). — An argument in favor of dropping Matter as an entity 

 and making Energy the sole basis of Metaphysics. It appears to 

 us quite inconclusive. g. f. b. 



8. Gravitation constant and mean density of the earth. — The 

 experiments on this subject begun in Spandau in 1884, at the 

 expense of the Konigliche Akademie der Wissenschaiten and 

 with the aid of the German government, have now been brought 

 to a conclusion. The complete account of the work appears in 

 the proceedings of the K. Akad. d. Wissenchaften of Berlin. The 

 method consisted in double weighing in two scale pans, separ- 

 ated by a connection 226 cm long. The authors, F. Richarz and 

 O. Krigar-Menzel, give as their first result 



A = (5-505±0'009) — 3 

 v ' ' cm 



The results obtained by previous observers are as follows : 



Observer. Method. 



Cavendish Torsion balance 



Reich " 



Baily 



Cornu and Bailie. " 



Ph. v. Jolly Balance with 



long supports 5'692 ±0068 

 J. Wilsing Pendulum ap- 

 paratus 5-594 ±0-032 



" Pendulum ap- 

 paratus 5 -5 V 7 ±0-013 



J. H. Poynting.. .Balance 5-4934 



C. V. Boys Improved tor- 

 sion balance. 5*5270 

 The German investigators F. Richarz and O. Krigar-Menzel 

 believe that of the above the results of Wilsing, Poynting and 

 Boys are the most accurate. Under certain assumptions Poynt- 

 ing's final result would have a less probable error than that of the 

 authors. Boys estimates that his best result has a probable 

 error of ±0002. The probable error of Richarz and Menzel is 

 1-6 per thousand.— Wied. Ann., No. 10, 1898, 177-193. j. t. 



9. Theory of the Coherer. — The experiments on wireless tele- 

 graphy have turned the attention of many investigators to the 

 obscure phenomena of the coherer. E. Aschkinass reviews the 

 theories of Branly, Lodge, Auerbach, Arons, D. van Gulik and 

 others, and points out that sufficient attention has not been paid 

 to the increased resistance of the coherer, due to electric waves. 

 Wireless telegraphy depends upon the diminished resistance 

 which allows a relay circuit to pass through the coherer. The 

 author describes many experiments which apparently contradict 

 the theory of Lodge and others that the increased conductiv- 

 ity is due to minute sparks, which bridge over the discontinuity 



Am. Jour. Sci.— Fourth Series, Vol. VI, "No. 36.— December, 1898. 

 35 



