ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
329 
means they are readily removed out of the optic line, thus effecting 
a great saving of time. The foot of the instrument can be made to 
reverse and lock, so as to bring the longest spread under the body-tube, 
when the instrument is to be used in a horizontal position for photo- 
graphy or drawing.* 
Fig. 76. 
Ross’s New Bacteriological Microscope. — This Microscope (fig. 77) 
has been specially designed for bacteriological study, and is one of the 
steadiest ever constructed for this 'purpose. The inclination to tilt, 
prevalent in many stands, is obviated by mounting on a patent modified 
tripod foot or a circular foot. This patent tripod gives a much greater 
spread than the ordinary tripod, but requires less space in the packing 
case, because the hind toe is made to fold forward between the two fixed 
front toes when not in use. The circular form of foot has the short 
stout pillar, supporting the upper part by a substantial knee-joint, 
situated towards the margin of the ring, which brings the whole weight 
centrally upon the foot when the instrument is in the upright position. 
When inclined, the centre of gravity is again brought directly over the 
foot, by rotating the pillar upon a reliable fitting at its base, so that 
absolute steadiness is secured. This is maintained with the body and 
limb in the horizontal position, so that the Microscope is particularly 
well adapted for photomicrography. The stage is firmly fixed between 
* This principle of the reversing foot was invented by Cuff, circa 1765 (see 
Journ. R.M.S., 1898, p. 675, fig. 117) ; it was used by Andrew Ross in 1842 (Journal, 
1899, p. 215, fig. 47), adapted to a horseshoe foot by Sidle and Poalk in America 
in 1880 (Journal, 1880, p. 523, fig. 39), and by Maclaren here in 1884 (Journal 
1884, p. Ill, fig. 9 .)— Ed. 
1899 
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