That for 1877 embraces 200 pages, and gives in detail the hourly observations, with their means and the wind-roses.

In the Bulletin Mensuel, besides the minute observations at the Observatory, there also appear numerous contributions from other portions of Eastern Asia. In the Bulletin for July will be found a description and an interesting series of diagrams, showing the successive changes in a waterspout observed near Shanghai.

The progress of meteorology is now seen to be so dependent on the prompt formation and study of daily weather maps, and this work is so materially assisted by the use of the electric telegraph, that we are not surprised to find combined in one person-Mr. Charles Todd, of Adelaide, South Australia-the various positions of government astronomer, meteorologist, and director of the post-office and telegraph lines. In this last capacity Mr. Todd has been able to greatly further the extension of the telegraph, and its utilization in weather study and predictions. Since January, 1876, he has published regularly the weather observations from about 80 stations, most of which send in daily reports by telegraph. His pamphlet entitled "Observatory and Climate of South Australia" contains a mass of details relative to the climate of the interior of Australia, which has hitherto been to meteorologists an unknown region. Similar bulletins are published by Ellery at Melbourne, and Russel at Sydney.

With the extension of telegraphic communication throughout Japan-where it is estimated that even now there are 125 stations in operation-it is confidently hoped that a system of telegraphic weather reports will be organized, possibly under the initiation of the Department of Public Instruction, at the head of which is Professor Murray, of New Brunswick, N. J. The Imperial University at Tokio, under the Department of Public Instruction, and the Imperial College of Engineering, under the Department of Public Works- the former under American and the latter under English influence-are both advocating such a system.

GENERAL TREATISES.

In our last annual summary a very brief note called attention to the publication by Blanford of the Indian meteorologist's "Vade Mecum," and the accompanying tables.

These important volumes are worthy of much more extended notice, and ought to be in the hands of every student of meteorology, and every observer as well.

The "Vade Mecum" is divided into two parts: first, instruction to observers; second, the meteorology of India. The instructions are certainly clear, without superfluous words, and every word to the point; and, while especially adapted to use in India, afford valuable suggestions for observers everywhere. The second part of " Vade Mecum" is what especially interests the student of meteorology, as distinguished from the mere observer, and in the introduction he states that in this part of his volume, a knowledge of the laws that regulate the internal movements of the atmosphere is the business immediately before us. He entertains the view, apparently very nearly correct, that in India we have an epitome of atmospheric physics, even as in England we have an epitome of strategraphic geology.

The author gives the most recent results in his next chapter on the physical properties of air and vapor. He especially calls attention to the erroneous custom, now rapidly becoming obsolete, of subtracting the tension of aqueous vapor from the total barometric pressure. The diurnal variation of vapor tension he partially explains as due to the ratio between the rate of production and the rate of removal. The effects of condensation of vapor in retarding the fall of temperature are very fully developed.

The conclusions of Tyndall in reference to the absorption of heat by aqueous vapor are not adopted by him; and he inclines, with most physicists, to adopt the conclusions of Magnus, confirmed, as they have been, by Hoorweg and Buff —namely, that air and vapor differ little in absorptive power; and that in atmospheric phenomena it is most important to distinguish between true vapor and that which is in the first stage of condensation. The results of direct observations on atmospheric absorption by Forbes, Hennessy, Hodgkinson, Neumayer, Strachan, and Harrison are adopted by Blanford to the general exclusion of purely physical theories.

The dynamic heating and cooling of the atmosphere, as deduced from the dynamical theory of heat, are very fully appreciated and exposed. The physical geography of India has, as in every country, the greatest influence over its me

teorology, and is very graphically presented in the second chapter. In the chapter on radiation and temperature, he states that the predominating feature of Indian meteorology is the semi-annual reversal of the system of winds, the primary cause of which is the variation in the quantity of solar heat, which is then followed out in all its details. From paragraph 62 we extract the following: "The maintenance of an ascending convection current over India in the rainy season, and of a descending convection current in the cold dry season, is in both cases consistent only with a vertical decrement of temperature less rapid than in regions where no such movement is in progress." In the chapter on atmospheric pressure and winds, Mr. Blanford first explains the laws that have been known as Dove's law and Buys-Ballot's law, as particular consequences of Ferrel's law. In the section on Indian monsoons the tables and diagrams showing the monthly variations of temperature, pressure, wind, and clouds are extremely satisfactory. He finds that the depth of the winter monsoon in January and February in the neighborhood of the hills is probably less than 7000 feet, while the summer monsoon is much more than 11,500 feet. The summer monsoon has a greater average velocity, depth, and volume than that of the winter, but a lower velocity than the winds of the hottest season. During the height of the southwest monsoon there is a region in the Arabian Sea in which the winds are light and the sea smooth; this is known to navigators as the soft place in the monsoon. To the north of this the monsoon

blows with great force.

The diurnal barometric oscillations are given for a number of stations, and the theory that Mr. Blanford proposes is ingenious, if not satisfactory. It is that originally worked out by Kreil and Lamont, modified by the fundamental assumption that the pressure exerted by the expansion of the lower layers of the atmosphere is only slowly communicated to the upper layers, and that the inertia of the latter, when once in motion, accounts for the barometric minimum in the afternoon. In the chapter on hygrometry, cloud, and rainfall, Mr. Blanford gives some comparisons between Wolf's sun-spot numbers and the register of rainfall at six stations in India since 1813. He finds the cyclical variation of the rainfall very distinctly indicated, especially from Madras.

In the chapter on storms, he considers that there is some reason to believe that the simoom has some special qualities besides heat and dryness, warranting its name of the poison wind, and that it should not be treated of merely as a case of hot wind.

The northwest wind of Calcutta advances from some point between northeast and west, or even southwest. The wind that precedes the rain is very cool, and is heralded by a sudden rise of the barometer. Wind pressures of fifty pounds to the square foot have been recorded on these occasions.

In the chapter on cyclones Ferrel's formula for gradients is applied to the case of storms in the tropics; and the angles of incurvature of the wind are given for several localities in the storm of October 15, 1874.

The monthly distribution of 115 cyclones in the Bay of Bengal throughout the year was as follows:

The origin of the cyclones, he finds, in accordance with his own and Mr. Elliott's investigations, is the production and ascent of a large quantity of vapor, which is condensed with the liberation of its latent heat over the place of its production, instead of being carried away to some distant region. He considers that there is a consequent local lowering of the atmospheric pressure, causing, or tending to cause, an indraught of air towards the place of minimum pressure.

Mr. Blanford would seem to imply that the barometric depression in the central portions of this region is mainly due to the ascent of vapor and its condensation; but it has already been shown by others that these alone can produce only a very insignificant diminution of pressure at the earth's surface; and the true explanation of the origin of the latter involves the consideration of the inertia, centrifugal force, and internal friction of the atmosphere. The volume closes with a very excellent chapter of suggestions as to subjects requiring further investigation.

Among the general treatises on meteorology there has been published one in Italian-the "Manual Nautico di Meteorologia," by Captain F. Viscovish, of the Austro-Hunga

rian Lloyd Service-in which special attention is, of course, given to the law of storms, and which shows a very general appreciation of the most recent works on this subject.

A little volume has been published, at the price of one English shilling, by Hoveste & Sons, London, entitled "Weather Warnings for Watchers, by the Clerk of the Weather." The book is mostly occupied with the details of instruments.

A series of articles on meteorological topics, by Captain Ansart, have appeared in occasional numbers of the Revue Maritime et Coloniale during 1874, 1875, and 1876. In these many new ideas and formulæ are propounded which are not likely to be generally accepted; and yet the work will repay attention.

Rev. Samuel Haughton communicates to the Royal Society of Dublin a geological proof, based on the examination of the fossils found in the earth, that the changes of climate in past times were not due to changes in the position of the earth's axis, and gives as the lower limit to the duration of geological time a minimum of 200,000,000 of years.

Dr. Woeikoff exhibited in the Russian section of the Paris Exposition a series of maps of isobars, isotherms, rainfall, etc., for the globe; and the "text explanatory," which has been widely distributed, shows that these charts, drawn from the best sources, are, in general, an improvement upon those produced by Buchan, Wild, Buys-Ballot, Coffin, Schott, etc.

On the climate, especially the temperature, of the United States, Woeikoff has published in the Austrian Meteorologische Zeitschrift an extended review, basing his tables and figures partially on the publications of the Smithsonian, Army Engineers', Army Signal-Office, New York and Canadian Meteorological reports, etc.

As a question of climatology, nothing can be more interesting than the fluctuations of Great Salt Lake, as these are now brought to light by the labors of Mr. Gilbert. It is to be hoped that he will also investigate some of the other lakes of the Rocky Mountain region, in order to eliminate the influences of purely local circumstances. Great Salt Lake was low from 1847 to 1850, was 5 feet higher in 1855, but again as low as before in 1861 and 1862; from 1868 to 1877 it has averaged about 10 feet higher than in 1850. A very ancient beach-mark that exists about 4 feet above