intelligence of their condition has been ages in speeding through space. The application of this fact to the appearance of nebulæ and what may be considered as worlds in course of formation, is not dwelt upon sufficiently; for just as we see the formed suns as they existed in past æons, so do we now observe the condition of nebulous masses as they formerly existed. Here, again, a little palæontology and archæology would have done the author no harm. Just as the Almighty has left us fossils in our terrestrial strata, flints in our burial mounds, and inscriptions upon our tombs to instruct us in the past history of the earth and its inhabitants, so He unfolds to us-not as with His all-seeing and omniscient faculties, but through the very imperfection of our senses, through our inability to leave the surface of our little earth, and the consequent necessity that we should stay here and await the intelligence of the past,-so, we say, he shows us the whole history of the universe at one glance, revealing to us to-day stages of formation and progress which existed at periods long past, in a ratio of time measurable by the space through which the message-bearing ray has had to pass in its mission of knowledge. In other words, as soon as our instruments enable us to measure the distance from us of a fixed star or nebula, and show us its condition, we are able to compute at what period of the past, reckoning backwards from to-day, the object we are viewing was actually in that condition, and we have therefore a more precise method of ascertaining the time which has been requisite to bring about cosmical changes than we at present possess for determining the periods required for the deposition of terrestrial

strata.

As to Mr. Proctor's views on "Supervision and Controul," they are as suggestive as all his other chapters, but they are not likely to gain much favour, from the author's timidity in expressing his views on controverted subjects. It is not difficult to guess what these are; but when a writer says he will give us an insight into the nature and operations of the Almighty, but he sees no advantage in making people uncomfortable by saying what he himself thinks on just those matters on which he is best able to form a judgment, his views of Divine action are not likely to be much heeded either by "believers" or "unbelievers." The book has other faults. It is of too mixed a character, treating in some places (as where the principles of the spectroscope are explained) of physical phenomena in terms suited for a schoolboy, and in others discussing controverted points in astronomy with the earnestness and particularity of an experienced disputant, and not always without the suspicion of some little unphilosophical animus.

No one will accuse us, after these criticisms, of having followed the too common but ignoble practice of handling tenderly, if not of flattering, the productions of a collaborateur, but we are bound to

say in conclusion, that we have been much charmed by the perusal of the work. It is in many places very poetical; its author shows himself to be a careful and earnest observer, and the novel aspects in which old phenomena are presented to the reader are deeply interesting and often startling. The beautiful chromo-lithographs are amongst the best we have seen, and they convey vivid impressions of the heavenly bodies which they are intended to represent.

COMPARATIVE LONGEVITY.*

MR. LANKESTER has published an Oxford prize essay on Longevity, and his little book merits the attention of a wider circle of readers than it would be likely to find within the precincts of the University. The title was, of course, not of the author's choosing, and as originally given out was as follows:- The Comparative Longevity of different Species of Lower Animals, and the Longevity of Man in different States of Civilization.' As the author very properly says in his preface, "The subject does not admit of very satisfactory treatment from a scientific point of view, and is accordingly one which probably few persons would have selected to write upon, unless under special circumstances," "but at the same time," he remarks, "longevity is a subject of great popularity, and hence the facts and arguments herein set forth may, it is hoped, interest the public."

Although we should not feel justified in complimenting the author upon his treatment of the question from any other than a scientific point of view, and are unable to accredit him with success in having imparted greater popularity to this subject, we have no doubt that the essay will materially add to his rapidly increasing reputation as an accurate observer and promising naturalist, for every page bears evidence of careful thought and extensive reading.

In conformity with the apparent wishes of the examiners or judges, he has divided his subject into two sections, the first of which treats of longevity in organisms generally, and the second of longevity in man.

His definition of longevity would be apt to puzzle non-scientific readers, for it is "the length of time during which life is exhibited in an individual;" but the meaning intended to be expressed, as subsequently explained, is that it is the "potential duration of life" in an "individual," as distinguished from a group or succession of individuals, as in the case of asexually-produced polyps, for ex

*On Comparative Longevity in Man and the Lower Animals.' By E. Ray Lankester, B.A., Oxon. Macmillan & Co.

ample. A reference to the author's carefully and conscientiously prepared "Statements as to the duration of the individual in organisms" (pp. 55 et seq.), shows upon what slender data he has been compelled to base his conclusions; for concerning whole groups, hardly anything appears to be known in this respect, and even where our knowledge is less scanty, line after line is preceded by the author's notes of interrogation.

His conclusions regarding the duration of life in the lower animals are as follows:

"Hence, in spite of the great complication of the case, we may conclude, on both deductive and inductive grounds, that the high or low potential longevity of different species, as a general law, is necessitated by those conditions of life which necessitate high or low individual development, as the case may be, whether of bulk, or complexity, or both, that it is directly subject to those conditions which cause personal expenditure to fluctuate, or which affect generative expenditure, being high when these are low, and low when these are high; that these relations, interacting and contending variously according to the special case, determine the potential longevity of the various species of lower animals.

"From the intricacy of these relations we may conclude that potential longevity is a very delicately balanced quantity, and that very slight causes may produce great fluctuations in it and be almost impossible to trace; the magnitude of the result being far larger in proportion to the magnitude of the initial cause, as is so often found to happen in biological science" (pp. 87-88). It may be as well to add, by way of explanation, that the author means by personal expenditure, "that involved in the wear and tear of assimilating food, and generally carrying on life" (p. 48).

When he comes to treat of longevity in man, his essay, as might be expected, is more popularly interesting, and its interest is enhanced by the originality of some of his observations. He attributes a longer life to man in civilization than in a state of nature. "Civilized man," he says, "lives in societies, one of the most essential bonds of union in which is the maintenance to a greater or less extent by the community of the feeble. The security which the healthy and vigorous man hopes for himself when grown old and feeble he naturally extends to others, and thus the aged are fed and protected as the result of a specific habit or characteristic among men (the most barbarous excepted)" (p. 88). This is the scientific re-statement of the commandment, "Honour thy father and thy mother, that thy days may be long upon the land which the Lord thy God giveth thee."

The author's account of the rise and spread of our race, and his partial application of Mr. Darwin's theory, only disappoint us by their brevity, and his conclusion is incontrovertible that "individual

men do not struggle for existence that is assured to them by society-they struggle "to get on." This is practical Darwinism, and the author shows that the expenditure of brain-power in man's case affects the potential duration of his life. He reviews carefully the phenomena bearing on this aspect of the question on savage and civilized life, and his conclusion is, "that a civilization of the highest order in which the efficiency of the community and the efficiency of the component individuals is greatest-in which there is the most harmonious action, the greatest happiness for the greatest number, the least excessive expenditure with the least luxury, where regularity and temperateness are innate characteristics, will be that state of civilization most favourable to longevity."

But there is a set-off against this: great thinkers do not live so long as those who take things more easily, and we find from his tables that less distinguished men in every profession enjoy longer lives (in one sense of the word "enjoy ") than those who are more distinguished. If the millennium were reached, "men would no longer die of disappointment, but would all attain 80 or 100 years. There is no apparent reason why longevity should not increase beyond that limit, and advance with advanced evolution, and the diminished expenditure implied in complete adjustment" (p. 128). There is, however, another matter to be considered: Will not the limited area of our globe be pretty well covered with human denizens before that happy day dawns upon us? and what then? However, that is a matter for posterity to consider; and meanwhile we cordially recommend Mr. Lankester's suggestive little volume to our biological readers.

CHRONICLES OF SCIENCE,

Including the Proceedings of Learned Societies at Home and Abroad ; and Notices of Recent Scientific Literature.

1. AGRICULTURE.

THE extreme drought of the past three months is by far the most important of recent agricultural events to put upon our record. Already, in early June, throughout the southern counties, pastures are becoming bare and brown, and spring-sown crops are dwindling. Clover and other forage crops are not yielding half their usual produce to the scythe; wheat alone has not yet materially suffered, but a continuance of dry weather must injure the wheat harvest too. Wheat, indeed, "needs no rain after May;" but that is only when May itself has soaked the ground. The usefulness of artificial manures depends very much on the wetness of the growing season. No applications in the way of top-dressings to growing crops are made when they would obviously be useless; and this great aid and stimulant to fertility being lost, the year's produce thus suffers indirectly also from the drought. The Cirencester Chamber of Agriculture has reported the favourable results of top-dressings of nitrate of soda and superphosphate of lime on the wheat and barley crops of the Cotswold soils. On three experimental plots, the average increase of grain per acre per 100 lbs. of the former dressing by itself was 276 lbs. The average increase per acre of four plots per 100 lbs. of the former together with 200 lbs. of the latter dressing was 517 lbs. of grain. In other cases the difference due to the added superphosphate was not so great; but the conclusion, upon the whole, seems to have been that nitrate of soda, applied as a spring top-dressing to wheat, whether by itself or not, yields a satisfactory increase of produce; though the result of the combined dressing of superphosphate together with the nitrate was still more satisfactory. The practice of topdressing grain crops in spring is a growing one; and as no one thinks of making this application, except in wet weather, this is an advantage which this year's harvest will have lost.

Dr. Voelcker continues to report to the Royal Agricultural Society of England the results of his constant analyses of commercial manures and cattle foods-showing to how much fraud and roguery English agriculturists are exposed. Guano is this year unusually various in its composition-even genuine Peruvian guano is sometimes damaged by sea-water, or contains an excessive quantity of sand. Samples are reported containing as much as 17 per cent. of water and 5 to 9 per cent. of useless mineral matter, and only 12 to 13 per cent. of ammonia-being thus worth less by 30s. or 40s. a ton than the price at which Peruvian guano is now sold.