In a previous communication it was pointed out that the effect of transverse magnetization on the resistance of nickel wire was inappreciable in fields below 500 C.G.S. units, thereby differing from the case of longitudinal magnetization, in which the effect was easily measurable in fields below 20. The reason of this is no doubt to be referred to the thinness of the wire in the direction of the magetizing force. To measure the effect of transverse magnetization it was necessary to form a fiat coil and insert it between the poles of a powerful electro-magnet. Considerable difficulty was experienced in winding this coil with interwound asbestos insulation, for great care had to be taken that no part of the wire cut the lines of force obliquely, otherwise there would be a resolved component of longitudinal effect, which in certain cases might altogether mask the effect looked for. The coil used in the final experiments was suitable in all respects. It was coiled between glass plates, the successive coils being separated by threads of asbestos. Round the coil another coil (of Beacon wire) was wound anti-inductively, so that any current passing through it would have no magnetic action upon the nickel wire inside. By varying the current in this external coil I was able to heat the nickel to any desired temperature up to 400° C. In any one experiment the final temperature came to a steady state, and not till this state was reached was it possible to begin the observations on the resistance change. This was measured in the manner already described in my paper on the effect of longitudinal magnetization, and it will suffice meanwhile to call attention to a remarkable result obtained when the temperature approached that at which nickel ceases to be strongly magnetic.

We have, during the last two years, made a series of observations upon specimens of Sagartia troglodytes which are at least fifty years old, and have thought it worth while to give a somewhat detailed account of these, as, so far as we can ascertain, there is only one other recorded case of longevity in Coelenterates (see p. 302), and very few in the whole of the Invertebrata.

In a former communication it has been shown that iron demagnetised by decreasing reversals of a directional force ab, develops an induction component at right angles to the subsequent magnetising force H, when the angle θ between these two forces is other than 0° and 90°. This component after reaching a maximum tends to disappear as saturation values are reached.

§ 11. The present communication is substituted for another bearing the same title, which was read before the Royal Society of Edinburgh on January 7th, 1887, because the result of that paper was rendered imperfect and unsatisfactory by omission of the exponential factor referred to in § 10 of my paper of February 1st, 1904. I shall refer henceforth to the last-mentioned paper as §1 …. 10 above.

I propose in this preliminary communication to lay before the Society some results of investigations in the theory of Seiches in a lake whose line of maximum depth is approximately straight, and whose depth, cross section, and surface breadth do not vary rapidly from point to point.

As the seiche disturbance is small compared with the length of the lake, I shall make the assumptions usual in the theory of long waves:—viz., that the squares of the displacements and of their derivatives are negligible.

The present paper is the continuation of a note sent to the Society in July of last year, and is for the purpose of describing the developed form of the spectrophotometer whose principle was indicated in that communication.

In the ordinary spectrophotometer and in Laurent's “half-shade “polarimeter, two neighbouring patches of light of the same colour but of different intensities are presented to the eye of the observer, who by an appropriate means reduces the intensity of the brighter until in his judgment it is brought down to the same intensity as the other. The accuracy of such a measurement must depend on two factors. The first factor is the accuracy with which the observer's eye can judge of the equality of the two patches of light, and the second factor is the accuracy with which the instrumental reading indicates the intensity of the comparison beam, i.e., of the beam whose brightness is reduced till it becomes equal to that of the other. Now it is found that in ordinary cases the error of the eye's judgment in such measurements amounts to about 4% or 5%, while the measurement of the instrumental regulation of the light can be made much more accurately.

(1) If the array in question be

its score of three-line determinants |a1b2c3|, |a1b2f3|,.… may be viewed as consisting of two complementary sets of ten, each of the first set containing at least two columns taken from |a1b2c3|, and each of the second set at least two columns taken from |f1g2h3|. Further, either set of ten may be viewed as consisting of one unique member and three sub-sets of three members each, the members of a sub-set being derivable from one another by performing the cyclical substitutions

(1) The fundamental propositions in regard to the sum of the signed primary minors of a determinant are—

(A) An expression for the negative sum of the signed primary minors of any determinant is got by taking a determinant of the next higher order whose first element is zero with the given determinant for complementary minor, and whose remaining elements are units all positive or all negative.

I. Axes of Compound Symmetry of the Second Order.

In recent years, since the more or less general adoption of the systematic classification of crystals under the thirty-two possible types of symmetry, it has become usual to dispense with the ‘centre of symmetry’ as one of the elements of crystal symmetry, and to adopt in its place the ‘axis of compound symmetry of the second order.’

We have already shown that removal of the spleen (1) or of the thymus (2) has very little effect on the animal economy. Since the spleen and thymus together comprise the largest amount of lymphoid tissue in the body of young animals, it would appear not improbable that although removal of either of these organs causes no marked disturbance, their simultaneous extirpation might be expected to give rise to some more manifest change. Friedleben (3) states that, while in his series of experiments no dog died of removal of the thymus, and that the removal of the spleen in young dogs does not influence the course of life, the simultaneous removal of the thymus and spleen causes a marked deterioration of blood formation, and leads to death.

The problem to divide the plane, without overlapping, into a network of regular polygons with the same length of side, has been completely worked out for the three geometries for the case in which the polygons are all of the same kind. The resulting networks are called regular

In October of this year (1904) there came into my hands a very interesting specimen of a young salmon. In round terms, the fish is 1 pound in weight and nearly 14 inches long.

In June 1904 I received an invitation from Sir John Murray to visit Scotland and spend three or four weeks in exploring the Scottish lakes, in order to make a comparison between them and the Danish lakes : he was of opinion that such a comparison of the lakes of a highland and a lowland country, which had hitherto not been attempted, would lead to some interesting results. The admirable bathymetrical and physical explorations carried on by Sir John Murray in Scotland, and more especially in Loch Ness, being far advanced, the question as to the scope of the biological observations called for consideration ; so he desired me to indicate, from the impressions derived during my visit, my views as to the most useful lines of investigation that might be taken up with reference to the biology of the Scottish lakes. I was much interested in the task imposed upon me, and at the same time gratified at the prospect of assisting in the design of the biological explorations in the lakes of a foreign country ; and as it was of the greatest significance to me to learn the nature of alpine lakes, I immediately accepted the invitation. I spent three weeks in Scotland,—the first two at, Fort Augustus, on Loch Ness, and the third in Edinburgh. From Fort Augustus I explored the lakes of the Caledonian Canal, and thus became acquainted with alpine lakes; from Edinburgh I explored a few lowland lakes, especially Loch Leven. The steamer Mermaid, belonging to the Marine Biological Station at Millport, fully equipped for deep-sea work, under the direction of Dr Gemmill, was sent into the Caledonian Canal, and many hauls were taken with the dredge and trawl, as well as with different kinds of tow-nets, in Lochs Lochy, Oich, and Ness, down to the greatest depths (500 and 750 feet).

In the summer of 1902, while working as a student in the Chemistry Department of Edinburgh University, I prepared a quantity of potassium chromoxalate (Gregory's salt) as an ordinary exercise, and this led me to attempt the preparation of a similar derivative of succinic acid, since such derivatives apparently had not been obtained.

The recognition of the importance of lateral strain in the theory of elasticity, as now taught in most engineering colleges, makes it very desirable that students should make experiments upon the lateral contraction of tension specimens and the lateral extension of compression pieces with the same facility that they now determine the values of Young's modulus and the modulus of shear.

In the Annual Report of the Smithsonian Institution for 1902 Prof. Langley has published an important note on “Good Seeing,” in which he describes some experiments undertaken with the view of improving the definition of telescopic images, so far as it depends on the conditions of the air in the vicinity of the instrument. Up to now the belief has prevailed among astronomers that in order to obtain good definitions the air inside the telescope-tubes should be kept as much as possible not only at a uniform temperature but also in a state of perfect tranquillity. Langley, however, shows that this view is not quite correct, and that maintaining constant and uniform temperature inside the tube, while preventing circulation between the air inside and outside the instrument, is not sufficient to produce satisfactory telescopic images. Particularly, this method does not diminish the troublesome boiling which in solar observations proves so often to be a source of grave inconvenience to the observer. But he shows that if the air inside and near the telescope-tube is agitated by stirring, the definition becomes at once markedly better. The improvement has in all cases been so decided that the reality of this beneficial effect of stirring cannot well be doubted.

The South Orkneys are a small group of islands situated in the Southern Ocean, in about 62° S. lat. and 45° W. long., roughly 800 miles S.E. of Cape Horn. A single landing was made from the “Scotia “on Saddle Island, a small island on the north side of the group, and another on Coronation Island, the largest and most westerly. With these two exceptions all the rock specimens were obtained on Laurie Island, the most easterly of the group.

The subject of the moon's development has been dealt with by Professor G. H. Darwin by means of a highly abstruse mathematical analysis, which the present writer cannot pretend to be able to discuss. He wishes to point out, however, that Professor Darwin's theory requires the assumption that earth and moon formed, at one time, a single highly-heated fluid mass; the theory being that the moon was thrown off by centrifugal force aided by the sun's tidal influence and synchronous vibratory motion of the fluid mass.

In this memoir the author described a Pennella found attached to the back of a Balænoptera musculus, specimens of which were given to him in 1903 by Mr Chr. Castberg. The specimens were of the same species as the Pennella balænopteræ described by Koren and Danielssen in 1857, and found infesting B. rostrata. The species is a giant Copepod, and the longest examples measured about 12½ inches.