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Mr. Sidebotham suggested that in using very high powers, 
such as the l-25th, if slips of mica were used for mount- 
ing the objects, together with mica covers, there would be no 
risk of damage to these lenses, which could thus be used 
in many examinations where the fear of damage now prevents 
their employment. 
Mr. Dancer exhibited a new and improved Oxycalcium 
Microscope ; the lenses were adapted to the ordinary form of 
lantern, and consisted of new combinations of lenses, giving 
a large flat field, and plenty of light, along with very fine 
definition. — The room was darkened, and Mr. Dancer ex- 
hibited an extensive range of objects with several powers, on 
a large stretched paper screen, 8ft. by 5ft., showing the 
application of this instrument to the uses of lectures on 
various subjects. Besides the usual objects, such as sections 
of wood, objects mounted in fluid, living animalculae, the pro- 
cess of crystalisation, electrical action, & c., were exhibited, 
A new combination forming a one-inch object glass for the 
achromatic microscope was also exhibited by Mr. Dancer, 
and was much admired. 
