A. M. Mayer—New form of Lantern-Galvanometer. 415 
controlled that it could readily be altered during the progress 
of the lecture; while finally, the arrangement of the a 
magnets had to be such as allowed me instantly to bring the 
needle into the magnetic meridian when disturbed therefrom, 
an yen lantern; while the front lens of the condenser 
around the axis of the lens. 
The horizontal condensing lens is five inches in diameter, 
and the magnetic needle is four inches long. With this arrange- 
ment I have obtained sharp and bright images of the graduated 
circle 16 feet in diameter. 
FP See: arrangement of lenses, which is due to President Morton, gives a bright 
7 eonny illuminated tield free from coloration. : 
cont, the Quarterly Journal of Science, Oct. 1871. is a report of Prof. Morton's ac- 
L t of this invention [* the vertical lantern”, delivered before the 
stitute, as follows: ‘The original idea and general plan of the instrument shown, 
hn Bo } essor J. P. Cooke, of ;_his 
chaniny ounection with it being confined to the devising of @ convenient me- 
rm arrangement of parts, the improvement of the combination of condensing 
reflecting lenses [mirror as to secure a white and evenly 
the i silv mirror 
