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Rh to total population of illiteracy, of church accommodation, of producers, etc., and the distribution of wealth, public indebtedness, taxation, revenue, expenditures, and agricultural products.

timely little volume was contributed in installments to Nature, and these are now collected and issued in the neat form of Macmillan's "Nature Series." It gives an interesting account of the general subject, first, in its historical aspect; second, the scientific conditions of the problem; third, the preparations for solving it by the different nations. The volume is copiously illustrated, and will meet the wants of general readers who wish to know something about the great scientific event that is to happen in December. At the close of the third chapter, the author thus recapitulates the technical view of the subject:

"1. We know the relative dimensions of the solar system accurately; but we do not know the scale.

"2. The determination of the distance of the earth from the sun, or from any of the planets, at a fixed date, fixes the scale.

"3. This may be determined (1) by the aid of a transit of Venus; (2) by an opposition of Mais; (3) by a knowledge of the velocity of light, combined with observations of eclipses of Jupiter's satellites; (4) by the velocity of light and the constant of aberration; (5) by the calculated effects of the sun's disturbance upon the lunar motions.

"4. A transit of Venus may be utilized:

"(a.) By the determination of times of contact at different stations, combined with a knowledge of the longitudes of these stations.

"(b.) By determining the least distance between the centres of the sun and Venus during the transit, observed from different stations.

"5. This last determination may be made by any of these methods:

 "(1.) The photographic method. "(2.) The heliometric method. "(3.) The method of durations."

—The twelfth volume of the "International Scientific Series" is contributed by Dr. John W. Draper, and will be a "History of the Conflict between Religion and Science." It might seem strange that such a history has never been written before, but the subject has had to wait for the historian. It is doubtful if there is another man living besides Dr. Draper who has had the peculiar preparation necessary for executing so difficult a task. Dr. Draper's familiarity with science is extensive. He has cultivated large tracts of it as an original investigator, and with a success that has given him a world-wide reputation. He has also been a life-long student of history, and has considered his questions largely from his point of view as a student of Nature. Dr. Draper's "History of the Intellectual Development of Europe" is one of the great books of this age; and that it is so appreciated is shown by the fact that it has been translated into nearly all the languages of Europe. The study of the problem of the intellectual development of man which has taken place in Europe in historic times, was a grand preparation for treating the special relations of religion and science in their historic aspects. The volume is written in a remarkably clear and attractive style, suitable for all readers, and it abounds in fresh and striking views, vividly and boldly presented. Dr. Draper's book is certain to make a profound impression upon the public mind.

the Preface to this complete edition of his Address, Prof. Tyndall says that it was written in the Alps, and was sent home in installments to be printed; but, being too long for oral delivery, he was compelled to omit certain parts, while only what he read was given to the public. The omitted passages are now supplied, the whole has been thoroughly revised, and a Preface is added in which the Professor pays his respects to some of his detractors. Regarding one of these imputations, he says: "In connection with the charge of atheism, I would