of science must be extremely careful not to allow the reins to get into unfit and incompetent hands.

In investigations which so completely baffle the ordinary observer, the thorough scientific man has a great advantage. He has followed science from the beginning through a long line of learning, and he knows, therefore, in what direction it is leading; he knows that there are dangers on one side, uncertainties on another, and almost absolute certainty on a third: he sees to a certain extent in advance. But, where every step is towards the marvellous and unexpected, precautions and tests should be multiplied rather than diminished. Investigators must work; although their work may be very small in quantity if only compensation be made by its intrinsic excellence. But, even in this realm of marvels,--this wonder-land towards which scientific inquiry is sending out its pioneers, can anything be more astonishing than the delicacy of the instrumental aids which the workers bring with them to supplement the observations of their natural senses?

The spiritualist tells of bodies weighing 50 or 100 lbs. being lifted up into the air without the intervention of any known force; but the scientific chemist is accustomed to use a balance which will render sensible a weight so small that it would take ten thousand of them to weigh one grain; he is, therefore, justified in asking that a power professing to be guided by intelligence, which will toss a heavy body up to the ceiling, shall also cause his delicately-poised balance to move under test conditions.

The spiritualist tells of tapping sounds which are produced in different parts of a room when two or more persons sit quietly round a table. The scientific experimenter is entitled to ask that these taps shall be produced on the stretched membrane of his phonautograph.

The spiritualist tells of rooms and houses being shaken, even to injury, by superhuman power. The man of science merely asks for a pendulum to be set vibrating when it is in a glass case and supported on solid masonry.

The spiritualist tells of heavy articles of furniture moving from one room to another without human agency. But the man of science has made instruments which will divide an inch into a million parts; and he is justified in doubting the accuracy of the former observations, if the same force is powerless to move the index of his instrument one poor degree.

The spiritualist tells of flowers with the fresh dew on them, of fruit, and living objects being carried through closed windows, and even solid brick-walls. The scientific investigator naturally asks that an additional weight (if it be only the 1000th part of a grain) be deposited on one pan of his balance when the case is locked. And the chemist asks for the 1000th of a grain of arsenic to be carried through the sides of a glass tube in which pure water is hermetically sealed.

The spiritualist tells of manifestations of power, which would be equivalent to many thousands of "foot-pounds," taking place without known agency. The man of science, believing firmly in the conservation of force and that it is never produced without a corresponding exhaustion of something to replace it, asks for some such exhibitions of power to be manifested in his laboratory, where he can weigh, measure, and submit it to proper tests.*

For these reasons and with these feelings I began an inquiry suggested to me by eminent men exercising great influence on the thought of the country. At first, like other men who thought little of the matter and saw little, I believed that the whole affair was a superstition, or at least an unexplained trick. Even at this moment I meet with cases which I cannot prove to be anything else; and in some cases I am sure that it is a delusion of the senses.

I by no means promise to enter fully into this subject; it seems very difficult to obtain opportunities, and numerous failures certainly may dishearten anyone. The persons in whose presence these phenomena take place are few in number, and opportunities for experimenting with previously arranged apparatus are rarer still. I should feel it to be a great satisfaction if I could bring out light in any direction, and I may safely say that I care not in what direction. With this end in view, I appeal to any of my readers who may possess a key to these strange phenomena, to further the progress of the truth by assisting me in my investigations. That the subject has to do with strange physiological conditions is clear, and these in a sense may be called "spiritual" when they produce certain results in our minds. At present the phenomena I have observed baffle explanation; so do the phenomena of thought, which are also spiritual, and which no philosopher has yet understood. No man however denies them.

The explanations given to me, both orally and in most of the books I have read, are shrouded in such an affected ponderosity of style, such an attempt at disguising poverty of ideas in grandiloquent language, that I feel it impossible, after driving off the frothy diluent, to discern a crystalline residue of meaning. I confess that the reasoning of some spiritualists would almost seem to justify Faraday's severe statement-that many dogs have the power of coming to much more logical conclusions. Their speculations utterly ignore all theories of force being only a form of molecular motion, and they speak of Force, Matter, and Spirit, as three distinct

* In justice to my subject, I must state that, on repeating these views to some of the leading "spiritualists" and most trustworthy "mediums" in England, they express perfect confidence in the success of the inquiry, if honestly carried out in the spirit here exemplified; and they have offered to assist me to the utmost of their ability, by placing their peculiar powers at my disposal. As far as I have proceeded, I may as well add that the preliminary tests have been satisfactory.

entities, each capable of existing without the others; although they sometimes admit that they are mutually convertible.

These spiritualists are certainly not much in advance of an alchemical writer, who says

"I asked Philosophy how I should
Have of her the thing I would.
She answered me when I was able
To make the water malliable,

Or else the way if I could finde,

To mesure out a yard of winde;

Then shalt thou have thine own desire,

When thou canst weigh an ounce of Fire;

Unless that thou canst do these three,

Content thyselfe, thou get'st not me."

It has been my wish to show that science is gradually making its followers the representatives of care and accuracy. It is a fine quality that of uttering undeniable truth. Let, then, that position not be lowered, but let words suit facts with an accuracy equal to that with which the facts themselves can be ascertained; and in a subject encrusted with credulity and superstition, let it be shown that there is a class of facts to be found upon which reliance can be placed, so far, that we may be certain they will never change. In common affairs a mistake may have but a short life, but in the study of nature an imperfect observation may cause infinite trouble to thousands. The increased employment of scientific methods will promote exact observation and greater love of truth among inquirers, and will produce a race of observers who will drive the worthless residuum of spiritualism hence into the unknown limbo of magic and necromancy.

If spiritualists would but attend to the teachings of their own prophets, they would no longer have to complain of the hostile attitude of Science; for hear what Thomas L. Harris urges, in his 'Lyric of a Golden Age!'

"The nearer to the practical men keep

The less they deal in vague and abstract things,
The less they deal in huge mysterious words--
The mightier is their power.

III. THE RATE OF GEOLOGICAL CHANGE. By H. M. JENKINS, F.G.S., Secretary of the Royal Agricultural Society of England.

PUBLIC opinion on questions of theoretical geology grows slowly, and usually precedes the statement of important speculations. The progress of discovery leads up to the induction, which, after floating more or less hazily in the minds of geologists for a certain time, is at last enunciated piecemeal at irregular intervals by the more daring theorists. Finally the scattered fragments are collected and arranged, bound together by the idea which connects them, and placed on record as a complete whole. This last is the task which I propose to attempt in reference to the progress of public opinion on the subject at the head of this article.

But first, let me clear the way by a short summary of the ideas which prevail amongst English geologists, so far as they bear on this subject. The prominent feature of the favourite modern school of geology in England-Uniformitarianism-is the belief that the forces in operation at the surface of the earth in former times differed in no appreciable degree from those now in action. This article of faith is, however, commonly restricted to what, for convenience of expression, has been termed "Geological time"-a period which is entirely represented by the rocks found on the earth's surface, from the oldest to those now in course of formation. According to this school, the rate of geological change has been approximately equal throughout the vast period which has elapsed since the deposition of the oldest stratified rock. Local variations of this law would doubtless be admitted by even the most thorough advocate of Uniformity, but the broad general principle characteristic of the creed is equality in the rate of change throughout all geological time.

Catastrophism, which is the name usually given to the other great school of geologists, is distinguished broadly by the tenet that in past times the forces in operation at the surface of the globe were of far greater intensity than they are now, and that great physical changes were then produced by more or less violent cataclysms. Probably there are geologists who now-a-days reject the catastrophes, but still cling to the belief that modern forces are much less intense, and modern changes much less rapid and extensive, than those which occurred in former geological periods. Therefore, whichever view we take of this theory, it is clear that its advocates believe that the rate of geological change was greater in past times than it is now; and the inference appears fair that, according to this school, the rate of change has, on the whole, progressively diminished from the earliest down to modern times.

In his Anniversary Address to the Geological Society last year, Professor Huxley defined a "third phase of geological speculation, namely, Evolutionism." This doctrine, in the words of the author, "embraces all that is sound in both Catastrophism and Uniformitarianism, while it rejects the arbitrary assumptions of the one, and the, as arbitrary, limitations of the other." To my mind it cannot well be distinguished from ordinary Theoretical Geology, unfettered by the trammels of any school; but obviously, the Evolutionist is prepared to accept whatever theory on the rate of geological change can be shown to be consistent with those known facts which can fairly be quoted as evidence.

en

The title of this article is capable of more than one interpretation, and in its various meanings it has already been investigated by speculative geologists. The late Professor Edward Forbes, in his lecture before the Royal Institution, "On the Manifestation of Polarity in the Distribution of Organized Beings in Time,' deavoured to show that the rate of development of generic types reached its maximum intensity, firstly, during the earlier Palæozoic periods, and secondly, during the later Neozoic periods; that is to say, near the beginning and the end of the geological scale. Again, the rate of development was shown to be at its minimum during the later Palæozoic (Permian) and earlier Neozoic (Triassic) periods, from which contiguous zero-points the development of generic types was asserted to increase in both directions.† This relation Professor Forbes termed "Polarity," and he showed how in several of the great divisions of the animal kingdom, two of their groups appeared to exercise a kind of "reciprocity," as, for instance, our old friends the Paleozoic four-starred corals versus the Neozoic six-starred. But Professor Forbes was careful to make the reservation that "the numbers of species in a group or genus at any given epoch is to be excluded, not being an element in the discussion of the question, though apt to be introduced through mistake of the nature of the generalization attempted to be attained." Indeed, the relations of individuals, species, and genera were favourite subjects of speculation with this poetic and philosophical palæontologist; and the generalization we have just sketched was a sequel to some other inquiries, in recording which he defines a genus as "an abstraction-an idea-but an idea impressed on nature, and not arbitrarily dependent on man's conceptions." Again, "a genus consists of more or fewer of these manies resulting from one [species] linked together, not by a relationship of descent, but by

*Notices of the Meetings of the Royal Institution,' vol. i., p. 428.

†This view may be correct; but at present, as at the time when it was advanced, we have only negative evidence in support of it; and it is still very possible that Permian and Triassic rocks, rich in generic types, may be discovered in some hitherto unexplored region of the earth.

'Notices,' &c., vol. i., p. 196.