Chemistry and Physics. 463 
It thus becomes manifest that the paleontological evidence bear- 
stion of the age of this formation, so far as yet 
Dinosaurian, the organic remains favor the conclusion that it is 
i The testimony of the plants, however, on this point, 
? 
quereux’s opinion, that the Bitter Creek plants are Tertiary, may 
upon specific identifications among them of forms known to 
; ” 
occur in well determined Tertiary rocks elsewhere. 
SCIENTIFIC INTELLIGENCE: 
I. CHEMISTRY AND PHYSICS. 
_1. Magnetic Equivalent of Heat.—M. Caztn has been inves- 
tigating the heat produced in the core of an electro-magnet when 
the current is alternately made and broken. Call m the induced 
From these facts it follows that to measure the magnetic equiv- 
; bobbin of stout and short wire to 
reduce the induction to a minimum, employ a weak current, and 
break it in a very resisting medium, that the circuit may be broken 
in as short a time as possible. 
The differential thermo-magnetic apparatus described, Comptes 
Rendus, Ixxviii, 845, serves to measure the increased pressure of a 
mass of air enclosed in the magnetized core after the circuit has 
