484 Scientific Intelligence. 
in every respect, ae eae use of it in the nase svasallh ae 
suggested no modification. As mounted upon its frame 
a height of about 125 centimeters, and the base covers a ice 
forty-five centimeters long and thirty-three wide. It is so light 
that it may readily be lifted and carried with one hand. The 
‘glass work was very skillfully constructed, after the design of 
the writer, by Mr. W. Baetz, of 96 Fulton street, New York City. 
Yale College, Nov. 14, 1881. 
‘SBCLENTIFEIC. INTELLIGEN CRs, 
J. Puysics AND ASTRONOMY. 
Dynamo - Electric Machines.—Sir W. Tuomson ee 
ds a simple mathematical analysis of the currents in a dynamo- 
rue machine, giving a continuous current, that the Heed 
= KR oes in which E is the resistance of the exterior 
ee and R e the resistances of the field magnets and the 
revolving Areal If r represents the ratio of the total work to 
! 
the lost work and «= the formula 7 = 1 + 2 ft results. The 
case considered is that of a dynamo-electric machine provided 
with a shunt circuit.— Comptes Rendus, No, 12, Repeeeness: hes 
p- 474. 
2; Rotation wed paw of parece of Light by the Earth's 
Magnetisi NRI BecquEREL states as the result of his ex- 
periments ny Be rays D traversing horizontally a column of sul- 
hide of carbon of 1” in length in a econ eee to the mag- 
netic needle, undergo at the temperature ° C. under the in- 
‘is n aamber consti tutes a natural Sapient by which we can con- 
vert into absolute <itiniyts he determinations of the magnetic 
ritatloits of the plane of piladieation of light, and by which we 
can express the intensity of a magnetic field i in terms of the rota- 
tion to which it gives rise, In the OC. G. S. system, the above re- 
sult is yee by 1°31 x 10 which denotes the magnetic rota- 
tion of the D lines in a magnetic field of strength unity, between 
two points at a sae of unity.— Comptes Rendus, ic 
red ae 88 1881, 
3. The value ofthe ‘Obie —Lord Rayieies and Sensei tage 
redetermined the ohm by means of the original apparatus used 
by the Committee of the British Association and have obtained 
the value 0,9893 = A adrant 
141, 1881. ne 
— Proc. Roy. Soe., xcii, pp. 104- 
