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achromatic adjustment amongst angle animals aperture apochromatic appear balsam beautiful objects better bull's-eye called cells centre cilia colour concave condenser cone corrected cost cover-glass cyclosis Desmids diameter diatoms easily edge Eotifers examined exhibit eye-piece filaments flat fluid focus focussed Foraminifera forceps give hairs high powers Hydrozoa illumination immersion inch Infusoria insects instrument interest known labium lamp larger layer lens lenses lower power magnified Messrs methylated spirit micro microscope microscopist minute mirror motion mounted nearly obtained ocular optical ordinary organs outer pair pencil peristome piece plane plants polarised light pollen-grains pollen-tube pond prism proboscis racked refracted refractive index retina ring Rotifers round screw sections seen shown in fig side slide spherical aberration stage stand stomata structure substage sufficient surface thick thin transparent trough tube usually varnish Volvox Vorticella wings
Page v - The wisdom of God receives small honour from those vulgar heads that rudely stare about, and with a gross rusticity admire his works : those highly magnify him, whose judicious inquiry into his acts, and deliberate research into his creatures, return the duty of a devout and learned admiration.
Page 155 - ... (Gypsum). I detected it in the form of an opaque white substance without lustre, and, to the naked eye, devoid of crystalline structure, in cakes and somewhat rounded masses varying in size from that of a small pea to that of a...
Page 152 - But undifferentiated protoplasm did not long universally hold the field. It was gradually shown that a distinct structure was discoverable in some cells, and subsequently it was show.n that nearly all cells and all forms of protoplasm show a microscopic network of fine fibres. In short, it became plain that the reputed structurelessness of the cell was due to the inefficiency of the lenses used, and was dissipated when competent optical aids were employed. Since this time great progress has been...
Page 73 - ... of the ohm at the hands of the great physicists of all nations. And it is intended that this redetermination shall result in a standard for general adoption. Thus electricity will be the first of the practical sciences to be freed from all difficulties due to local standards ; and it is to be hoped that this example may be followed in other sciences concerned with practical life. The following are the actual resolutions adopted by the International Congress of Electricians at the sitting of September...
Page 30 - ... front. To get a geometric measure for comparison, he took the radii, or half diameters (whose relative proportions would be the same), and which, geometrically, are the sines of tlie semi-angle of the outermost rays grasped.
Page 222 - We cannot enumerate all the various kinds ; but one of the most interesting (from this point of view) is the ciliated cell.
Page 33 - Rayleigh shows that the above measure of resolution is only possible with a square aperture, or one bounded by straight lines parallel to the lines resolved.
Page 22 - ... the edge of the lens come to a focus nearer the lens than the central rays. The image formed by the large reading glass in § 8, on close examination will be found rather blurred from this cause, which is called