they can wield their influence by means of maintaining the unity of the language. Certain circumstances make it possible for them to do so; thus the teachers and professors mostly come from the States of New England. If these influential men truly comprehend the destiny of their country, they will use every effort to transmit the language in its purity; they will follow classic authors, and discard local innovations and expressions. In this question of language, real patriotism (or, if you will, the patriotism of Americans really ambitious for their country) ought to be, to speak the English of Old England, to imitate the pronunciation of the English, and to follow their whimsical orthography until changed by themselves. Should they obtain this of their countrymen, they would render to all nations and to their own an unquestionable benefit for futurity.

The example of England proves the influence of education upon the unity of a language. It is the habitual contact of educated people and the perusal of the same books which, little by little, is causing the disappearance of Scotch words and accent. A few years more, and the language will be uniform throughout Great Britain. The principal newspapers, edited by able men, also exercise a happy influence in preserving unity. Whole columns of the "Times" are written in the lan. guage of Macaulay and Bulwer, and are read by millions of people. The result is an impression which maintains the public mind in a proper literary attitude.

In America the newspaper articles are not so well written; but the schools are accessible to all classes, and the universities count among their professors men especially accomplished in their use of the English tongue. If ever there should arise a doubt in the opinions of the two countries as to the advisability of modifying the orthography, or even making changes in the language, it would be an excellent plan to organize a meeting of delegates from the principal universities of the Three Kingdoms, of America, and Australia, to propose and discuss such changes. Doubtless they would have the good sense to make as few innovations as possible; and, thanks to common consent, the advice would probably be followed. A few modifications in the orthography alone would render the English language more easy to strangers, and would contribute toward the maintenance of unity in pronunciation throughout Anglo-American countries.

NOTES BY DR. JOHN EDWARD GRAY, OF THE BRITISH MUSEUM. It may be observed, in addition, that the people who use the English language in different parts of the world are a reading and a book-buying people, and especially given to the study of quasi-scientific books, as is proved by the fact of the extensive sale which they command.

In support of this assertion, I may quote the Baron Férussac's review of Wood's "Index Testaceologicus," in the Bull. Sci. Nat., Paris, 1829, p. 375. He remarks:

"We observe with interest the number of subscribers that exist in England for an octavo volume on shells, costing 186 francs. It is a curious fact, which booksellers and authors will appreciate, as it will afford them the means of seeing how a return is obtained for their outlay on such works in England, compared with other countries. The number of subscribers is 280, of which 34 are females and 6 foreigners. Certainly all the rest of Europe could not produce as many, nor perhaps even the half of that number."

How much more astonished would M. Férussac have been, if informed that these were only the subscribers before publication, and that 1,000 copies were sold! Since 1829 the sale of scientific books has much increased, as is shown, for example, by the many editions of the works of Lyell and other naturalists, each edition being of 1,000 copies. Most scientific books in France and other continental countries can only be published when the government furnishes the cost; and they are chiefly published in an expensive form as a national display, and are almost confined to their public libraries, except the sale of copies that are bought by English collectors.

In England such works are generally published by individual enterprise, and depend on the general public for their support, and are published in a style to suit the different classes. Thus there are works of luxury for the rich, often published by individuals who confine themselves to the production of that class of books; very cheap works for the student and mechanic; and books of all intermediate grades, produced by the regular publishers. The females of all grades are extensive readers of this class of books, which, I believe, is chiefly the case with English-speaking races.

Some of the scientific Swedes and Russians have published their papers in the English language, or appended an abstract in English to them, as Thorell on European Spiders; Professor Lilljeborg on Lysianassa, and Professor Wackerbarth on the Planet Leda, &c. The Danes and Dutch often publish their scientific papers in French, as Temminck, Reinhardt, and the late Professor Van der Hoeven, who themselves read and write English; but it appears they regard French as the polite language of courts, and forget that courtiers, geuerally, have a contempt for science, and that they should look among the people for their readers.

It is to be observed that Professor de Candolle himself uses the French language with a very English construction; but we believe that his work would have commanded the greatest number of readers if written in the English language, which he reads and writes so fluently.

See, also, Mr. Galton's interesting article on the Causes which create Scientific Men, in the "Fortnightly Review" for March, 1873, p. 346, which contains some interesting observations on M. de Candolle's work.

ON UNDERGROUND TEMPERATURE.

Prepared for the Smithsonian Institution by CHARLES A. SCHOTT, of the U. S. Coast Survey.

The earth's solid crust being hotter than the mean temperature of the lower atmosphere resting on its surface, heat is constantly and very slowly passing outward, and strata of equal depth would have very nearly uniform temperatures but for the influence of the daily, the annual, and the irregular variations of the atmospheric temperature, received by conduction. The solar heat then acts as a disturbance of the thermal equilibrium, and the depth of the stratum of the so-called “invariable temperature," i. e., when the changes escape ordinary observation or become less than 0°. 01 C., as generally defined, is found about 6 meters below the surface in the tropics, and about 30 meters below the surface in the middle latitudes. The corresponding depths at which the daily variations become imperceptible are 0.3 meter and 1.3 meter very nearly. These numbers, however, depend greatly on the kind of soil or rock, and will differ considerably for loose soil of greater or less porosity and for solid rock. Our records of observations are very scanty and deficient in range, and barely afford the necessary data to form a basis of calculation, on account of the many conditions which enter into the problem.

It would appear from experience that the mean temperature of the air, as ordinarily observed, say at an elevation of 1 or 2 meters above ground, is slightly higher than the mean temperature of the surface of the soil. The mean temperature of the earth's crust increases from the surface, with increasing depth, and with a nearly uniform rate for moderate depths, with an average amount of about 28 meters for each degree of the centigrade scale, and the temperature at the depth of invariable heat nearly equals the mean annual atmospheric temperature of the place, but slightly exceeds it in amount. For greater depths the descent to produce an increase of 10 C. is greater than the amount given above. With increase of depth the amplitude of change is rapidly diminishing, and for a depth increasing arithmetically the amplitudes diminish in geometrical ratio; also the depth at which the daily and annual variations, respectively, disappear is in proportion of the square root of the length of these periods, or about 1 to 19. The amplitude 4p has been represented in the form, log 4 p = A— Bp, where A and B are constants to be determined at the place, and p the depth. Observations by Quetelet at Brussels, for instance, give the following result: log 4p 1.15108–0.04149 p, (amplitude in degrees centigrade and p in

=

feet.) At this place the following mean temperatures and epochs of maxima have been obtained :

For the greatest depth, the time required for the heat-wave to reach it is nearly six months, making the surface maximum temperature coincident with the minimum temperature of the stratum, 7.32 meters below.

In the case of Chicago, we may take the mean annual temperature of the atmosphere just above the surface-80.17 C.; that of the surface of the soil 80.0 C. The increase for a depth of 12.2 meters for the lowest stratum of clay and to the rock-surface will be 0°.44 C., making 80.44 C. for this depth. The invariable temperature may be estimated about 9 or 10 C., and may be found at a depth between 30 and 40 meters, the variations being transmitted to a greater depth in rock than in clay. At the surface of the rock the variations of temperature will probably yet amount to 00.1, (according to the Edinburgh observations.) For a depth of 229 meters, corresponding to the depth from which the wellwater flows, the increase of heat should amount to 8°.2 C., according to the mean given above; hence the computed temperature 160.2 C. But the observed temperature is only 120.8 C., showing either a much slower rate of increase (1° C. in 48 meters) or a local deviation, probably due to infiltration of water from a higher level. Whether the lake-water, which is colder at the same depth than solid matter would be, can exert an influence by conduction, I do not know.

Prof. J. D. Everett, chairman of the committee of the British Association for the Advancement of Science, on the subject of underground temperature has published a number of valuable reports The following is an extract from a recent communication of his to the Belfast Natural History and Philosophical Society:

"The phenomena of underground temperature may conveniently be classed under two heads, according as attention is directed to the first forty or fifty feet, or to such depths as are attained in mines and artesian wells.

"The annual wave of temperature is propagated downward from the surface, at a rate which depends on the nature of the soil, and is on the average rather greater than a foot per week; while at the same time the amplitude (or magnitude) of the wave diminishes in a ratio also dependent on the soil, and amounting on the average to a halving of the amplitude for every five or six feet of descent.

"Supposing the soil to be uniform, the surface to be plane, and the propagation of heat to be effected solely by conduction, a simple harmonic variation of temperature at the surface (which we may call in popular language a simple wave of temperature) will be propagated downward with a uniform velocity, and with amplitude diminishing in geometrical progression. There will, moreover, be a definite relation between the ratio of this progression and the velocity of propagation, so that if the one is given the other can be computed. In fact, we shall have

where denotes 3.1416; c, thermal capacity per unit-volume; and, k, conductivity.*

"If the variation of temperature at the surface, instead of being simple harmonic, be any periodic variation whatever, it can be reduced by Fourier's method to the sum of a number of simple harmonic variations, and each of these variations will be propagated according to the above law, unaffected by the rest.

"As the square root of the number of days in the year is almost exactly 19, the above formula shows that the annual wave is propagated 19 times as fast as the diurnal wave, and that the falling off in amplitude is the same in one foot for the diurnal wave as in 19 feet for the annual wave. "Of the different simple harmonic components which make up the whole variation at the surface, those of longest period are propagated downward most quickly, and die away most slowly. For this reason,

*The numerical value of the co-efficient

√, as given in Professor Everett's Discus

k

sion of the Observations at the Greenwich Observatory, 1860, is as follows:

The diminution of

indicates either a decrease in capacity for heat or an increase

in conductivity.