G. F. Barker—New Vertical-lantern Galvanometer. 207 
bon compounds obtained existed in the iron, and that it had in 
part broken up at the temperature of the experiment into carbon 
(remaining united with the iron) and carbonic anhydride (which 
escaped as gas), yet, in view of the steady decrease in the quan- 
tity of this latter gas collected as the experiment proceeded and the 
temperature became higher, and bearing in mind the ready decom- 
position it undergoes in contact with ignited iron, it seems imore 
likely that a larger amount of carbon originally existed in the 
iron in this higher state of oxidation than appears from the fig- 
ures of the analysis.” 
the end was not raised to as high a temperature. Both these 
circumstances would of course facilitate the escape of the car- 
bon dioxide and diminish the chance of its undergoing partial 
reduction by prolonged contact with strongly heated iron. 
whole I confess that I cannot look upon the above 
quoted conclusion reached by Prof. Wright as sustained by 
the scanty evidence as yet before us. 
Art. XXXI.— Contributions from the Physical Laboratory of the 
University of Pennsylvania. No. 1.—A New Vertical-lantern 
Galvanometer; by Gzorcr F, Barker, M.D., Professor of 
Physics. 
[Read before the American Philosophical Society, May 7, 1875.] 
ter was devised for the purpose, which has answered the object 
80 well that it seems Pkt to make some permanent record 
Various plans have already been proposed for ing visible 
to an audience the oscillations of a galvanometer needle ; but 
they all seem to have certain inherent wk poo which have 
tance of the scale, and this without impairing the delicacy of, 
