Determination of the Orientation of a Parent β Grain from the Orientations of the Inherited α Plates in the Phase Transformation from Body-Centred Cubic to Hexagonal Close Packed

Knowledge of the orientations of several α plates inherited from the body-centred-cubic–hexagonal-close-packed phase transformation of a β grain allows us to determine the orientation of the latter, provided that a strict orientation relation between the two lattices exists. This contribution discusses the problem of the uniqueness of the solution and leads to the conclusion that the number of different α orientations required for that purpose is three in the less favourable case but is reduced to two in the most favourable case.

P.M.R. spectra of heteroaromatic molecules containing bridgehead nitrogen atoms. III. Pyrrolo[2,1-c][1,2,4]benzotriazine

The detailed assignment and analysis of the p.m.r. spectra of solutions of pyrrolo[2,1-c][1,2,4]benzotriazine in dimethyl sulphoxide at 80� and 100�, and in acetic acid at 60�, was carried out. The presence and approximate magnitudes of several inter-ring long-range coupling constants were deduced by comparison of the experimental and theoretically calculated spectra. Spin-tickling experiments were used to determine the relative sign combinations of the intra-ring coupling constants of the protons 1-3 and 6-9 in the particularly favourable case of the acetic acid solution of pyrrolo[2,1-c][1,2,4]benzotriazine. All coupling constants were found to have the same sign, presumably positive.

Chemistry of the Podocarpaceae. XL. Conversion of methyl 12-Hydroxypodocarpa-8,11,13-trien-19-oate into Methyl 13-hydroxypodocarpa-8,11,13-trien-19-oate

Methods for the conversion of methyl (+)-12-hydroxypodocarpa-8,11,13- trien-19-oate (7) into the synthetically more useful compound methyl (+)-13-methoxypodocarpa-8,11,13-trien-19-oate (8) have been investigated. In the most favourable case, the transformation has been effected in c. 57% yield by a five-stage sequence involving hydrogenolysis of the 13-amino-12-tosylate (31) with Raney nickel.

Captain Cook and the transit of Venus of 1769

The motions of the planets among the stars even if observed with instruments capable of no greater accuracy than one minute of arc can be analysed to produce orbits whose relative sizes are known quite accurately. Kepler, for example, gave the correct shape of the planetary orbits as ellipses with the Sun in one focus. He was also able to assert that the squares of the periodic times were proportional to the cubes of the semi axes major, without being able to determine the length of any one of these axes in terms of the mile. As a matter of fact he thought that the scale was less than onesixth of what we now know it to be. To calibrate the scale of the planetary orbits against a terrestrial scale it is enough to measure any one interplanetary distance by triangulation from a terrestrial base line, of which the angle at the apex is necessarily small. So long as only the classical planets were known, the most favourable case is presented by the planet Mars, which approaches to within a distance of 4278 times the diameter of the Earth. Under the most favourable condition (of observing Mars at its closest approach from opposite ends of a diameter of the Earth) the angle at the apex of the triangle would be 1/4278 radian or 48 seconds of arc (so that the parallax, which is the semiangle, is 24 seconds of arc). There are many reasons why an accurate determination of the parallax of Mars was not easy to be accomplished by seventeenth-century astronomers. However, if early astronomers had settled the parallax of Mars at its closest approach to the Earth, they would have known the ratios of the distance between the planet and the Earth to the distances of either body from the Sun, from the orbits whose relative sizes were perfectly well known.

Measurements of the rate at which Helium is produced in Thorianite and Pitchblende, with a minimum estimate of their antiquity

The method of deducing a minor limit to the age of minerals from an examination of their radioactive properties has, up to the present time, depended on a measurement of the amount of helium they now contain, and on an indirect calculation of the rate at which it is being produced by the radioactive matter within them. There is not now much uncertainty about this calculation. Nevertheless, considering the fundamental importance of the question of geological time, it is not superfluous to determine in some favourable case by direct volume-measurement of the gas how much helium is produced per gramme of the mineral per annum, in order to see how long the quantity found in the natural mineral would take to accumulate, and to check the method of calculation to which we must still resort where the much more difficult direct method is impracticable.

XIX.—On the Histology of the Blood of the Larva of Lepidosiren paradoxa Part II. Hæmatogenesis

In the first part of this memoir I described the structure of the corpuscles at a stage of larval development when the red cells were actively dividing and the blood contained several varieties of white cells. During the course of these more strictly cytological observations, it was impressed upon me that the great size of the elements and their very marked histological characters, combined with the simple character of the organisation of the animal, made Lepidosiren a very favourable case for the study of the first principles of Hæmatogenesis. I was specially interested in what may be termed a middle phase in the history of the blood. I refer to a period after the primitive corpuscles have acquired haemoglobin and there are leucocytes present, but before the blood-forming organs are unfolded. This stage lasts a relatively long time in Lepidosiren up to the differentiation of the spleen, as the liver takes no part in blood-formation at any period.