Proceedings of the Cambridge Philosophical Society: Mathematical and physical sciences, Volume 6

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Cambridge Philosophical Society, 1889 - Science
 

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Page 138 - Ox, are given by the equations u = x cos 6 + y sin 6, v = — x sin 0 + y cos 6\ x = x cos 6 + y sin 6, y...
Page 221 - Pcrichata from New Zealand. CAMBRIDGE. Philosophical Society, May 21.— Mr. JW Clark, President, in the chair. — On solution and crystallization, by Prof. Liveing. When a substance passes from a state of solution into the solid state, the new arrangement of the matter must be such that the entropy of the system is a maximum ; and, other things being the same, the surface energy of the newly formed solid must be a minimum. If the surface tension be positive, that is tend to contract the surface,...
Page 74 - There seems, then, no escape from the admission that neither physical geology nor palaeontology possesses any method by which the absolute synchronism of two strata can be demonstrated. All that geology can prove is local order of succession. It is mathematically certain that, in any given vertical linear section of an undisturbed series of sedimentary deposits, the bed which lies lowest is the oldest. In...
Page 74 - ... for which there is not a shadow of proof, under the one common term of "contemporaneity" becomes incalculable, and proves the constant source of gratuitous speculations.
Page 30 - ... are perforated so as to place the cavities of successive segments in communication, the authors observed that, in the quiescent winter condition of the bulb, there are patches of callus — easily made conspicuous by staining with corallin — on the transverse walls. From this they infer that the transverse walls are perforated, the canals through them being open in the active, and closed by callus in the quiescent, condition of the bulb, just as is the case with sieve-tubes. This inference...
Page 213 - there are certain animals to which the above general considerations as to the distinctness of the coelom and the vascular system do not apply." The animals here referred to are the Hirudinea and the Nemertea. In a later paper Sedgwick suggests the possibility that the nephridial funnels of Leeches might possibly open into a closed vesicle which lies in, but does not open into the vascular system. That some such structure may have been overlooked is rendered more probable when one recalls the number...
Page 127 - AVhilst doing this care must, be taken that the collector does not himself spread the disease by carrying the refuse loosely. Rotation of crops, or, when this is impossible, deep trenching, would lessen the chance of the disease appearing. 7. Diseased plants may be treated with a mixture of powdered sulphur and freshly burnt quicklime sprinkled by hand or by bellows; or they may be washed or sprayed with a weak solution of iron sulphate (green vitriol). In both cases the- fungus is destroyed without...
Page 28 - The ccelom appears in the ordinary manner as a series of cavities, one in each mesoblastic somite. The somites, which are at first ventro-lateral in position, soon acquire a dorsal extension and the cavity in each of them becomes divided into two parts, — a ventral part which passes into the appendage, and a dorsal part which comes into contact but does not unite with its fellow of the opposite side on the dorsal wall of the enteron.
Page 121 - We must now obtain an expression for the modified Lagrangian function. Let the coordinates of a dynamical system be divided into two groups 6 and ^, the latter of which does not enter into the expression for the energy of the system.
Page 29 - The spaces are in communication with each other. The heart arises as a part of a which becomes separated from the rest. Posteriorly it acquires paired openings into the pericardium. It thus appears that the heart and various divisions of the body cavity of the adult form a series of spaces which have nothing to do with the coelom. They all communicate with each other and seem to form a series of enormously dilated vascular trunks, of which the heart is the narrowest and alone possesses the property...

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