I have taken advantage of the late meeting of the British Association, at Exeter, to bring the subject before meteorologists. It appears that the general term meteorology embraces two entirely distinct subjects, one of these having reference to physiology, while the other forms a branch of physical research.
The object of the one is to study the connexion between atmospheric conditions, and the health of such organisms (animal and vegetable) as are subjected to these conditions; while the other or physical question is particularly concerned with the movements of the earth's atmosphere, and with the causes thereof.
On both of these important branches we are in almost entire ignorance. With respect to the first, the amount of vapour present in the air is without doubt a very important element of climate, inasmuch as this affects in a marked manner the skin of the human body, and the leaves of plants; but I am not aware that it has yet been determined by the joint action of naturalists and meteorologists what is the precise physical function expressing proportionally the effect of moisture upon animal and vegetable life. Is it simply relative humidity? or does not a given relative humidity at a high temperature have a different effect from that which it has when the temperature is low? There is, in fact, an absence of information as to the precise physical formula which is wished by physiologists, as expressing the effect of moisture upon organic life.
If we come in the next place to consider the physical branch of meteorology, or that which regards the motions of the earth's atmosphere, this is almost as far behind. The explanation of the trades and anti-trades is the one great generalisation which we have accomplished. Certain laws regarding cyclonic storms have lately been discovered; but to this day we are in ignorance of that exact motion of air which constitutes a cyclone, some holding that the motion is entirely rotatory, while others maintain that there is a considerable indraught of air from the circumference to the centre. Again, there is no fact better established than the diurnal movements of the barometer; but what is the motion of air or its constituents implied by them is still a point open to dispute. Now, these are both matters of fact, and there must be some reason why we know so little about them. Nothing, of course, could be known until the instrumental difficulties of the problem had been surmounted, and a suitable anemometer constructed; but now, we have good instruments, and have begun to make good observations. What, then, is the remaining drawback? I believe it is to be found in the fact that while instrumental appliances and observations have progressed, methods of reduction, which naturally lag behind observations, have not yet progressed, but are only just beginning to move. Those hitherto in use combine the physiological with the physical element,—they are a cross between the two, and are subject, I venture to say, as all such crosses are, to the general law of barrenness. Still not much time has been lost, for in the dark ages of few and bad observations it would have been useless to divide the meteorological field: meteorology, then, might be likened to one of those organisms of very low development that had just begun to exhibit the slightest possible tendency to split into two; the application of the knife would then have been premature; but now it may be used with advantage, and the one half allowed to rush into the arms of physiology, while the other seeks the embrace of physical research. In plain language, if we want to obtain physiological results we must reduce our observations with especial reference to physiology, while if physical results be desired, they must be reduced with especial reference to physical laws.
I must, however, reserve for another article a description of a method of reduction having this latter object in view. Balfour Stewart
PREHISTORIC TIMES
WE may be pardoned for not being cosmopolite enough to judge books without any regard to their nationality. Too often, though Englishman may have contributed much to some important subject, no systematic English treatise sums up the evidence, so that our students have to depend too much on foreign books of reference. On the present subject of prehistoric archæology, however, it is satisfactory that we have, in Sir John Lubbock's work, not only a good book of reference, but the best. Its well-known plan and argument need not be re-stated here, but it has to be pointed out that the present edition contains much important new matter, especially in the chapters relating to the Stone Age, Megalithic monuments, Cave-men, and the condition or modern savages.
It is a marked character of the recent researches in prehistoric archæology, and it is one of the reasons which justify the reception of the subject as a department of positive science, that the facts disclosed lend themselves to generalisations of a thoroughly scientific character; and that, moreover, when the generalisations are once made, new facts drop in and find their places ready. Various subjects discussed in the present work illustrate this: take, for instance, the stone-implement question. The finding of flakes, scrapers, spear-heads, &c. in different parts of the world, justified a general surmise that the Stone Age had once prevailed in all inhabited districts. A few years ago, however, there were regions whence stone implements seemed hardly forthcoming. India appeared to have none, but when properly looked for they proved abundant, as witness Mr. Bruce Foote's paper in the Transactions of the Norwich Congress of 1868. Africa also seemed almost outside the Stone Age world; but now the finding of stone implements in South Africa, and even legends of their use, give the primal Stone Age possessions there as elsewhere. No sooner, too, were the rude implements of the Drift type thoroughly recognised in the valley of the Somme, than it came into notice that such had long before been collected in England without knowledge of their special importance; and now Spain and India, and other districts, furnish specimens which come under the same class. So it was with the art of fire-making by friction of pieces of wood. Over most of the world, savage or civilised, the traces of its early prevalence were sufficient to justify its being generalised on as one of man's primitive arts. But there were some exceptional cases, as in Tasmania, where the natives were said to
