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1846; the other is also a rapid lens, but is was made this year, and is only an inch long and an inch in diameter. Both lenses are for the same plate, viz., 10 by 12 inches.
A hand camera in 1884, for a 5 by 7-inck plate was as big as a full grown valise. Near the specimen in the case is a hand camera of 1890, and it is comparatively a baby in point of size.
The instantaneous "shutter" that was regarded as perfect in 1858, is nothing but a brass slide with two holes in it for exposures. It is a crude looking affair when compared with the beautiful piece of mechanism alongside it-the instantaneous shutter of to-day, in which the movement of the iris of the eye is imitated precisely and by which as short an exposure as the 150th part of a second is possible.
The development of the signal service weather maps is made plain on a large board, but there is no evidence to show that the weather has improved with the maps. A row of mutilated poker-chips is immediately below the specimens of ancient and modern meteorological prophesy.
Side by side are the original Joseph Francis car and an improved version of the same great invention.
The Benjamin Franklin hand press is under glass in the center of the room and so is a collection of time-indicators-sun dials, clepsy^[[dra,]]