The differential equation of the conduction of heat in ordinary three-dimensional space is generally written in the form

where v denotes the temperature of the medium at time t. For a medium in which the temperature varies only in one direction, e.g. an infinite cylinder with the temperature varying along the axis, the equation is

In the Proceedings of the Royal Society of Edinburgh for 1921–22 Whittaker suggests an atomic model designed to absorb and emit radiation by quanta. This model consists essentially of a system of radial magnets, set as the spokes of a wheel with like poles (say south) at the centre. The electron approaching the wheel along the axis of symmetry will, according to the author, set the wheel into rotation, giving a “magnetic current.” The action of the approaching charge, giving a rotation to the North Pole and a “magnetic current,” is quite the analogue to the North Pole approaching a non-axial electric charge, setting it into rotation, and producing an “electric current.” The electron, with energy exceeding a definite value, succeeds in going through the atom, with the result that a definite amount of energy is permanently transferred from the electron to the atomic wheel, a result which resembles the absorption of electronic energy by the atom in spectrum excitation.

Unilateral ligation of the vas deferens in the mammal is a method now commonly employed in the surgical treatment of senility. The demonstrably beneficial results that follow the operation are explained on the assumptions that the testis is an endocrine gland; that if the gametogenic function is embarrassed, the interstitial tissue, regarded as the source of the sex-hormone, undergoes hyperplasia; and that associated with this increase in amount of tissue there is an increased elaboration of the internal secretion.

In order to examine the hypothesis, so ably enunciated by the Steinach school, that senility is a phase of life that is attended by, perhaps even caused by, the inefficient functioning of one or more of the components of the endocrine system, the writer set out upon a series of attempts to evoke rejuvenation in the aged fowl. In a previous communication (Crew, 1925) an account was given of an unsuccessful attempt to produce this result in the aged cock by means of unilateral vasoligation. In this paper the results of thyroid administration to aged birds of both sexes are reviewed.

Il est fréquemment nécessaire de mesurer, avec la plus haute précision possible, les intervalles de temps compris entre des signaux inscrits sur un appareil enregistreur (signaux horaires, tops d'observations astronomiques, etc.). Lorsque l'intervalle de temps à mesurer est de courte durée, on peut utiliser divers procédés, par exemple un diapason entretenu électriquement sans contact au moyen d'un amplificateur à lampes et dont on inscrit le courant d'entretien sur le même enregistreur. Il est aisé d'évaluer l'intervalle à mesurer en nombre de vibrations et fraction de vibration. Si cet intervalle dépasse quelques secondes, le procédé devient impraticable et il est nécessaire de subdiviser l'intervalle à mesurer en fractions d'une seconde par exemple, de compter le nombre entier de secondes intercalées entre les deux signaux et de ne mesurer en vibrations du diapason que les résidus compris entre le premier signal et la lère seconde, le dernier signal et la seconde la plus voisine de lui.

The function which is discussed in the greater part of this paper was introduced by Professor E. T. Whittaker in vol. xxxv (1915), pp. 181–194 of these Proceedings. A one-valued function, analytic in the finite part of the plane save possibly for poles, is taken and a table made of the values of f(x) for x = a, a + w, a — w, a + 2w, a — 2w, … The function

called the Cardinal Function, is then shown to be the simplest function satisfying the table of values so obtained, in that it is a function which, when analysed into its periodic constituents, has no rapid oscillations.

The highest member of the series of normal dibasic acids hitherto obtained by electrosynthesis is hexadecane dicarboxylic acid, HOOC.(CH2)16. COOH. In attempts to synthesise by this means dicarboxylic acids of still higher molecular weight, the following difficulties are encountered:—(1) The temperature of the liquid undergoing electrolysis must be kept above the melting point of the synthetic di-ester, in order that the latter may not solidify on the anode and prevent the passage of the current; (2) the alkali ethyl salts of the higher dibasic acids are of a soapy nature, and cannot readily be dealt with in concentrated solution. Two of the conditions favourable to electrosynthesis, high concentration of the electrolyte and low temperature, are thus unattainable.

Our knowledge of the anatomy of Dicksonia is mainly based on the description of D. Barometz given by Gwynne-Vaughan. The stem of this species possesses a radial dictyostele, which, on account of the shortness of the leaf gaps, is not far removed from the solenostelic condition. The leaf trace arises as a broad ribbon of tissue with inwardly folding margins, which soon, however, breaks up to form a horse-shoe of isolated strands.

About six years ago I communicated to the Society an account of some measurements made at Eskdalemuir Observatory of the more minute changes which are almost continually occurring in the vertical component of the earth's magnetic field. The method adopted was that of connecting the terminals of a coil of wire, whose axis is vertical, to a suitable galvanometer on which was measured the current induced in the coil by changes in the vertical component of the terrestrial field.

It is now a thoroughly well-established fact that a satisfactory match to any coloured light observable in nature can be made by a combination, in suitable proportions, of three standard lights suitably chosen from a spectrum. It is customary to choose for the standards a red, a green, and a blue light of definite average wave-length in each case. The greatest deviation from the average is made so slight that there is no visible difference in colour between the extreme components present in any one standard. A simple way (used by Maxwell) of obtaining these standards would be by means of an ordinary spectroscopic arrangement in which light is focussed on a slit, and is parallelised by a collimating lens, after which it passes through a prism and the object glass of a telescope, on whose focal plane a spectrum is thus formed.

About 1876 the author had occasion to devise a method of indicating the rate of flow of a liquid through a pipe system, without interfering with the flow. For this purpose he used a ball, heavier than the liquid, in a slightly tapered glass tube, through which the liquid flowed from the narrower to the wider end. In the first instance the tube was set vertical, with the wider part above. The ball fitted more or less closely at the lower end: it was carried up by the current till the clearance round it became such as to suit the particular rate of flow. Its height was read off on a scale fixed alongside of the tube, and served to indicate the rate of the flow, once the relation of scale-reading to flow had been experimentally determined.