The first work of this class which has been published is that of the the Rain-fall. It included all the material which had been collected down to 1866. It is now proposed to publish a new edition of this work, containing the additions since made, with improved maps, on a larger scale.

The next work of the same class is that on the Winds of the Globe, comprising the result of the discussion of not only the observations made under the direction of the Smithsonian Institution in the United States, but of those of every other part of the world of which the records were attainable. This work, to which the labors of Prof. J. H. Coffin, of Lafayette College, were for many years devoted, was nearly completed at the time of his death, has been continued by his son, Prof. Selden J. Coffin, and is now in the press. Very little, however, was done by the elder Coffin in the way of stating, in general propositions, the results contained in the large number of tables which he had elaborated. To supply this deficiency the Institution has fortunately been enabled to avail itself of the assistance of Dr. A. Woeikof, member of the Geographical Society of Russia, and late secretary of its meteorological commission, who, visiting this country for the study of its climatology, cheerfully undertook the required task.

The printing of this work is very expensive. It will occupy an entire volume of the Smithsonian Contributions, and comprise upward of 600 quarto pages of tabular matter, besides the letter-press. It will, however, we are confident, form a contribution to knowledge which will be a lasting monument to the industry of Professor Coffin and to the policy of the Smithsonian Institution.

The next work of the same class is that on the Temperature of the United States. It has been in progress at the expense of the Institution for a number of years. It includes the result of the discussion of all the observations which have been made in this country from the earliest times down to the present. It is illustrated by three maps of isothermal spaces-one exhibiting the annual, another the summer, and the third the winter distribution of temperature-and a number of diagrams incorporated in the text. It has been from the first under the direction of Prof. Charles A. Schott, of the Coast Survey, assisted by a number of computors, at the expense of the Smithson fund. The maps have been drawn and are in the hands of the engraver, and the whole work will be printed and distributed during the present year. It will form the first trustworthy approximation to an exhibition of the temperature of the various portions of the United States which has ever been published. The preparation of it has been more expensive than any other work ever undertaken by the Institution.

Another work in progress is that relative to the geographical distribution in the United States of thunder-storms, the frequency of their occurrence in different seasons, and effects produced by discharges of lightning, as compiled from all the records of the Institution during

twenty-five years. The preliminary labor was the collection and arrangement of a full list of stations at which thunder-storms have been recorded, the number of observations at each place, the time of beginning and ending of each storm, and the whole number of thunder-storms occurring in each year, and during the whole time at each place. From these data the relative frequency of thunder-storms in different parts of the country can be determined; also their relative frequency in different seasons and years, as well as the extent of the area over which they occur on the same day. The attending casualties, collected from all the observations made by several hundred observers during a period of twenty-five years, when brought together and classified, will strikingly illustrate the operations of one of the most energetic agents of nature. For the preliminary arrangement of the materials preparatory to scientific deductions from them, the Institution has employed Mr. George H. Boehmer.

Another series of reductions relative to the meteorology of North America which will occupy the attention of the Institution is that of the discussion of the observations on the barometer in various parts of the United States. This will be commenced as soon as the other series of investigations are completed.

Comets.-The first research relative to these I have to mention is that relative to a comet of short period or one that returns after a few years. Of these, there are at present six known, namely, Encke's, which has a period of about 33 years; Winnecke's, of between 5 and 6 years; Biela's, of 63 years; Faye's, of 73 years; Tuttle's, of 13 years; and Halley's, of about 76 years.

All the other comets which have entered the solar system have never been known to return, their orbits having probably, in many cases, been changed by the perturbations of planets in whose vicinity they may have passed.

The motion of the periodical comets is an object of great interest to the astronomer, as well as to the general physicist, in its relation to the question of the existence of a retarding medium filling interplanetary spaces, and therefore it is considered an object of much importance, not only to observe their successive positions at their periodic returns, but also to calculate with great precision their orbits as affected by planetary perturbations. At a meeting of European astronomers in August, 1873, the work of discussing all the observations which have been made on four of these comets was parceled out among the continental astronomers, Halley's comet having previously received great attention from the English and other astronomers; and the fifth, that of Tuttle, discovered by an American astronomer, was left to be worked out in this country. This task has been undertaken at the expense of the Smithsonian Institution, under the direction of Prof. Ormond Stone, late of the National Observatory, and now professor of astronomy in the

University of Cincinnati.

Professor Stone has chosen for this work a number of assistants, and will proceed with the reduction and discussion of the observations made on this comet at its several returns as rapidly as his other labors will permit.

The perturbations of the first order have been calculated, and the zerostars used in determining the place of the comet at the time of its last return in 1871 have been re-observed with the Washington meridian Circle. An accurate determination of the orbit traversed by this comet in 1871, as based on the corrected position of these stars, has been in part completed.

In this connection it may be interesting to state that of the one hundred and forty* asteroids discovered during this century, forty-two were first observed by American astronomers. It is not enough, however, that these bodies should be noted as planets, and their positions marked in the heavens for a given epoch; it is also necessary that their orbits should be accurately determined, and an ephemeris of each of them calculated by which its place can be ascertained at any future time. This work, however, is one, as it were, of approximation, and must be continued through a series of revolutions of each planet. In regard to the asteroids discovered in Europe, the investigation of them is under the charge of European astronomers; while for the investigation of those discovered in America, Congress has made an appropriation for the last three years, to be expended under the direction of Professor Coffin, director of the American Nautical Almanac.

Efficiency of steam-heaters.-Another investigation, at the partial expense of the Smithsonian Institution, has been undertaken under the direction of General W. B. Franklin, late of the United States Army, at the Colt's Fire-Arms Manufacturing Company, Hartford, Conn., by Mr. C. B. Richards, of which the following is an account:

The experiments which are proposed will be in continuation of two series already made, to ascertain the relative efficiency of the different kinds of steam-heaters used for warming buildings, and to determine also the laws of their operation. The first series related to what are known 23" direct radiators," and in these the heaters were exposed in a large room whose temperature could be changed and regulated as desired. In the second series the heaters were of the kind called "indirect radiators," and were inclosed in a flue through which currents of air were passed. The initial and final temperatures, the barometric pressure, and the moisture of the air were noted, and the quantity passed through the flue was measured by a Casella meter.

In both series the pressure of the steam was measured by an accurate mercury column, and its temperature was noted, while the heating effect of the heater was calculated from data obtained by collecting, cooling, and weighing the water of condensation obtained from the steam which was passed through the heater.

*Since the above was written two additional asteroids have been discovered.

Very satisfactory and consistent results were arrived at from the first series. But in the second series, the cost of the apparatus, the many different circumstances which it was necessary to take into account, the consequent greater care and time required in the investigation, and a lack of money with which to pursue the inquiry to the proper point, prevented the establishment of trustworthy data.

The importance of deciding the questions which it is the specific ob ject of these experiments to answer need not be urged. There is, how ever, one interesting circumstance which, among others, was observed, and which may be of importance outside the principal question. This relates to the determination of the condition of the steam as regards its dryness when it entered the heating apparatus; and, as a small quantity of steam was occasionally allowed to escape after it had passed through the heater, (in order to carry off air,) it was also desirable to ascertain whether any very considerable amount of water, in the condition of mist, was carried away by this escaping steam.

Hirn's method was employed in these determinations. Although the apparatus for this purpose was crude, and for precise experiments would require to be much improved, the experiments seemed to indicate clearly that the steam was nearly if not quite as dry, after passing over the condensing surface of the heater, as before; that is to say, its "mistiness" was not increased by its passage over a large extent of condensing surface. These results, if fully verified by a longer series of experiments with better apparatus, would indicate that there is a fallacy in the generally-entertained idea that "wet steam" is supplied to an engine if the originally dry steam is led through a long pipe.

The records of the experiments are voluminous, and it is intended to tabulate them, and to represent the results by curves when the whole are completed.

Elevations. It has been mentioned in previous reports that the Institution has been at considerable expense in collecting the profiles of canal, railroad, and other surveys, in order to the construction of a topographical map of the United States. The charge of this work was given to Mr. Nicholson, topographer to the Post-Office Department, but, owing to the absorbing nature of his official duties, he has been unable up to this time to complete it. In the mean while Mr. Gardner, of the Hayden expedition, has rendered an important service to this investiga tion by settling, through critical comparison of various surveys, the actual height of several important places in the interior, which will hereafter serve as points of departure for other surveys.

Natural History and Ethnology.-Various researches have been made. in natural history and ethnology, the actual expense of which has been defrayed by the Institution, without salary, however, to the person in charge of the work; an account of which will be given in a subsequent part of the report.

INTERNATIONAL EXCHANGES.

The Smithsonian system of international exchange still continues to render an important service to the advance of civilization, and emphatically to carry out the second clause of the will of Smithson for the increase and diffusion of knowledge among men—that is, mankind. It is the medium of exchange of literary and scientific materials between the United States and all foreign countries.

The effect of this system on the diffusion of knowledge can scarcely be too highly estimated. Thousands of works, containing the details of the latest inventions and discoveries, are through its means annually brought to this country, while a knowledge through the same medium is disseminated abroad of everything that is doing in the United States to promote a higher civilization.

As an evidence of the high estimation in which this part of the operations of the Institution is regarded, we may again mention that the Smithsonian packages are passed through all the custom-houses of the world free of duty and without examination, and, moreover, that they are transmitted free of cost by the principal transportation companies, namely:

Pacific Mail Steamship Company.
Panama Railroad Company.
Pacific Steam Navigation Com-

pany.

New York and Mexico Steamship
Company.

New York and Brazil Steamship
Company.

North German Lloyd Steamship
Company.

Hamburg American Packet Com-
pany.

French Transatlantic Company.
North Baltic Lloyd Steamship
Company.

Inman Steamship Company.
Cunard Steamship Company.
Anchor Steamship Company.

The special thanks of the Institution are again due to the above-mentioned companies for their enlightened liberality.

The following are the foreign centers of reception and distribution of the Smithsonian exchanges:

London-Agent, William Wesley, 28 Essex street, Strand.

Paris-G. Bossange, 16 rue du 4 Septembre.

Leipsic-Dr. Felix Flügel, 12 Sidonien Strasse.

St. Petersburg-L. Watkins & Co., 10 Admiralty Place.
Amsterdam-F. Müller.

Milan-U. Hoepli, 591 Galeria Cristoforia.

Harlem-Prof. Baumhauer.

Christiana-Royal University of Norway.

Stockholm-Royal Swedish Academy of Sciences.
Copenhagen-Royal Danish Society.

The following table exhibits the number of foreign establishments. with which the Institution is at present in correspondence, or, in other words, to which it sends publications and from which it receives others. in return: