This instrument consists essentially of a cryophorus, one bulb of which is kept wet by the same arrangement as is used for a wetbulb thermometer, while the other bulb is left dry. For convenience, the wet bulb is made spherical, and the dry bulb is made cylindrical, and is graduated. The difference of temperature between the two bulbs produced by evaporation causes a transference of water from the dry bulb to the wet bulb, and the amount of water thus transferred in any period of time, taken along with the mean temperature, will give a measure of the average hygrometric condition during that time. Preliminary observations with this instrument show that even in comparatively moist weather the total evaporation during twenty-four hours is great enough to be easily measured.

This instrument consists of a close spiral of insulated copper wire bent into the form of an anchor ring, so as to form an endless solenoid. The spiral is placed in a rectangular groove turned on the edge of a wooden or brass ring of suitable thickness and diameter. Short lengths of wire at both ends of the copper spiral are left straight. These, after being well insulated, are twisted together and led to two terminals, which serve as electrodes. The ring containing the spiral is fixed on a base board with its plane vertical, and at right angles to the magnetic meridian, when the instrument is in use. A short magnet, rigidly attached at right angles to the lower end of a stiff wire, is suspended from a silk fibre, so that its centre is in the circular centre line of the anchor ring.

If one closes a galvanic circuit containing a small battery, the electromotive force of which is not able to decompose water, and a voltameter with two platinum plates dipping into water acidulated with sulphuric acid, the current has a great intensity in the first moment, and diminishes at first very rapidly, afterwards slowly. At last its intensity approaches to zero more and more, but it never ceases completely, The more sensitive the galvanometer by which you measure its intensity, the longer the time during which you are able to observe the deflection of the needle. If the electrolytic fluid is in contact with atmospheric air, it is easy, even with a galvanometer of simple construction and moderate sensibility, to observe that at last a feeble residue of current remains, keeping a nearly constant intensity. This intensity, however, is increased by the slightest motion of the fluid, also by feeble motions produced by changes of temperature.

Scopo della presente piccolo comunicazione di mostrare con tin asempio notevole, ed in connessione colla teoria conosciuta delle rappresentazione piana di una certa classe di superficie, e con quella delle trasformazioni razionali nello spazio, come da un sistema piano di punti, rette e curve si possono dedurre la costruzione e le proprieta di superficie situate comunque nello spazio (di quelle che sono rappresentabili pun to per punto sul piano).

In setting about the construction of the Canon of Logarithmic Sines, we naturally look for any means of lessening the heavy labour of the undertaking.

It is frequently remarked that the science of statistics, in its various branches, is, like the law, “gloriously uncertain,” and accordingly, it is alleged that, from the same set of figures, two intelligent men can draw very different conclusions. The same assertion may, perhaps even more truly, be made regarding facts, which, although considered somewhat “sair to ding,” are very differently interpreted by different individuals. Interested motives, preconceived opinions, and illogical conceptions constitute some of the principal causes of perverted conclusions; and both facts and figures are very liable to misrepresentation. Hence the tendency in many quarters to distrust the deductions drawn from figures of almost every kind, more especially in the columns of official reports and the prospectuses of commercial enterprises. Even among intelligent and educated men, some strangely confused ideas prevail respecting statistics, many such persons erroneously supposing that every class of numerical facts ought to possess an equal amount of certainty and precision, similar to what is produced by the abstract figures of an arithmetical process.

The following paper gives the result of a considerable number of experiments made in 1883, the object of which was to ascertain whether any of the disinfectants in popular use had a “germicidal” action or not.

J'ai montré dans mon Cours d'Analyse de l'École Polytechnique, comment le procédé élémentaire d'intégration des fractions rationelles peut-être modifié de manière à donner l'intégrale lorsqu'elle est algébrique et ne contient pas de logarithmes, sans avoir d'équations a résoudre, Une question toute semblable se pose à l'égard des intégrales de la forme ou P, Q, R, sont des polynômes entiers en x, et j'en ai exposé la solution dans un article du Bulletin des Sciences Mathématiques de M. Darboux (C. vii. 1883). Mais la méthode que j'ai donnée peut être présentée sous une forme plus facile et plus simple; c'est ce que je me propose de montrer, et avant d'aborder les intégrates hyperelliptiques, je considérerai d'abord celles des fractions rationelles .

When I communicated my first note on this subject on the 21st of January last, the only definite conclusion I had then arrived at was that the very remarkable and brilliant colour effects, lately seen in the heavens at sunrise and sunset, were due to the presence of an unusual amount of dust at the time floating in our atmosphere.This atmospheric dust acts as a sifting medium, breaks up the white light into its components, and reflects all the different colours to us from different parts of the sky.

In meteorological observations the temperature of the air is of the first importance, and it is a subject to which a great deal of attention is given, thousands of temperature observations being made and recorded every day. It is therefore desirable that these observations shall be as correct as possible. At first sight nothing seems more simple than to take the temperature of the air. All that appears necessary is to hang up a correct thermometer of any construction, anywhere out of the sun, and the thermometer will then indicate the temperature of the air where the instrument is placed. We shall presently see that this is very far from being the case; and not only so, but we shall find that it is difficult to get two thermometers which will give the same readings, when hung near each other in the open air, even though they agree perfectly with each other when placed in water.

Ever since the Royal Society, Edinburgh, was pleased to accept my paper in 1880, on the general appearance of Gaseous Spectra, as seen on a very small scale; but complete on that scale from end to end of the visible spectrum,—I have been desirous of presenting them with some very highly-dispersed views of the more intricate portions of those spectra.