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Page 581 - ET DE PHYSIOLOGIE COMPARÉES, contenant des recherches sur 1° les lois de la symétrie dans le règne animal ; 2° le mécanisme de la rumination ; 3° le mécanisme de la respiration des poissons; 4° les rapports des extrémités antérieures et postérieures dans l'homme, les quadrupèdes et les oiseaux ; par P.
Page 6 - Hook used to look upon the magnified object with one eye, while, at the same time, he viewed other objects, placed at the same distance, with the other eye. In this manner, he was able, by the help of a ruler, divided into inches and small parts, and laid on the pedestal of the microscope, as it were, to cast the magnified appearance of the object upon the ruler, and thus exactly to measure the diameter which it appeared to have...
Page 44 - ... has tended to raise the compound microscope from its primitive and almost useless condition to that of being " the most important instrument ever yet bestowed by art upon the investigator of nature," and has gained for the discoverer a lasting reputation.
Page 9 - ... as because that light itself is a heterogeneous mixture of differently refrangible rays. So that, were a glass so exactly figured, as to collect any one sort of rays into one point, it could not collect those also...
Page 71 - But these hopes were disappointed: everything that ingenuity and perseverance could accomplish was tried by Mr. Varley and Mr. Pritchard, under the patronage of Dr. Goring. It appeared however that the great reflective power, the doubly-refracting property, the colour, and the heterogeneous structure of the jewels which were tried, much more than counterbalanced the...
Page 258 - ... cases it falls upon the surface in the same manner ; or, what amounts to the same thing, the beam of solar light has the same properties on all its sides ; and this is true, whether it is white light as directly emitted from the sun, or whether it is red light, or light of any other colour.
Page 73 - The specimens tested were rectangular in outline, and from an inch to an inch and a half in diameter. These were dried in a water bath (temp.
Page 192 - Huyghens for telescopes, with no other view than that of diminishing the spherical aberration by producing the refractions at two glasses instead of one, and of increasing the field of view. It consists of two planoconvex lenses, with their plane sides towards the eye, and placed at a distance apart equal to half the sum of their focal lengths, with a stop or diaphragm placed midway between the lenses.
Page 416 - Micrasterias, Closterium, &c., are generally situated at the bottom of the pool, either spread out as a thin gelatinous stratum, or collected into finger-like tufts. If the finger be gently passed beneath them, they will rise to the surface in little masses, and with care may be removed and strained...
Page 406 - It is also desireable to change a small portion of the water ; but this should be done without agitation. The best vessels for cultivating this plant in, are either wide pans, holding three or four gallons, or glass jars a foot or more high ; into these the Chara may be placed, either with clean water alone, or a little earth may be sprinkled over it, so as to keep it at the bottom, or the bottom may be covered one inch with closely pressed mould, in order that the water may be put in without disturbing...