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Abbe achromatic condenser alteration aperture aplanatic apochromatic back lens brilliant camera lucida Canada balsam cedar oil central centring screws colour screen comp compensating oculars cone Continental correct tube-length cover-glass critical illumination critical image dark diameter distance draw-tube dry condenser dry lens easily edge examine expanding stop exposure eyepiece eyepiece micrometer f-in field film fitted flame image fluorite focussing glass front lens Giemsa give ground hole holoscopic inclined iris diaphragm Leitz lenses light liquid paraffin low power magnifying power makers margins measure method micro microscope microscope board millimetres mirror mounted Nelson nosepiece oil immersion condenser oil immersion objective optical index ordinary illumination photographs photomicrographic piece placed position quarter plate rack the condenser Ramsden disc refractive index require rotate seen slightly Spirochceta pallida spirochete stage micrometer stained stop carrier sub-stage condenser surface trypanosome tube TVin uncovered object unmounted Watson whilst xylol Zeiss
Page 101 - D.VAN NOSTRAND COMPANY are prepared to supply, either from their complete stock or at short notice, Any Technical or Scientific Book In addition to publishing a very large and varied number of SCIENTIFIC AND ENGINEERING BOOKS, D. Van Nostrand Company have on hand the largest assortment in the United States of such books issued by American and foreign publishers. All inquiries are cheerfully and carefully answered and complete catalogs sent free on request.
Page 34 - ... and when the illumination is critical. " Critical Illumination. — An object is said to be illuminated critically when it is placed at the apex of a solid axial cone, the aperture of which is not less than three-quarters of the NA of the observing objective.
Page 27 - The ideal screen for visual microscopic work is .one which, filtering out the too pronounced red, softens down, but does not entirely cut out, the orange and yellow lights.
Page 43 - Solo playing is not the end of music; it is only a means to an end, and that end is Art.
Page 21 - One hour of steady hard work with the microscope by diffused daylight will tire you more than a whole day's work in a dark room by lamplight.
Page 93 - If there be a microscope in the world more likely to be influenced by vibration than any other, it is Powell's No. 1, for it has a long body and a long bar movement ; nevertheless, during all the years it has been in use not a single negative has been lost through vibration, and what is more, I never heard of any one else losing one from that cause.
Page 8 - ... of the image I am not prepared to admit. With regard to mirrors, a good deal of misapprehension exists. It matters little whether the mirror be dusty, or scratched, or the silver in bad condition, the only effect these will have will be to cause a little less light to fall on the back lens of the condenser, a matter supremely unimportant. An old scratched dull mirror will yield as critical an image as the finest worked up silver on glass Newtonian flat. The three things that are of paramount...
Page 14 - NA had a vast amount of empty magnifying power, while on the other hand the 24 and 12mm. will both stand a higher eyepiece than 10 ; nay, even require it before the detail resolved by them is made visible to the eye. It also shows that the...
Page 85 - The rule is, never mind where you project your image, but wherever it happens to come, there place your plate. The things of primal importance are the obtaining of a visually critical image, and the correct projection of that image, but the exact position of that image has no importance.
Page 27 - Experiments show that a normal eye is more sensitive in picking up fine detail when the light is a peacock green. " Although with light high up in the spectrum the resolving power of a lens is increased, yet the sensibility of the eye is diminished. The art is to strike a happy mean between the two.