speculations resting on a more or less reasonable basis; and, on the other hand, oftentimes a too tenacious retention of what is merely traditional interpretation, or a clinging to quotations from uninspired records as though they were divine utterances. I think it more befitting to my present position however, that I should address myself especially to younger students of natural science, with a view to pointing out some of the mistakes which they perhaps are particularly liable to fall into, mistakes which no doubt further study would enable them to correct for themselves, but which often remain uncorrected very much because the studies are so fitfully pursued that it is only when some circumstance arouses a public interest in scientific subjects that their attention is drawn to them again. It may appear but a commonplace observation when I say that one of the first things to be guarded against is impatience of the drudgery needful to master even the alphabet of almost any branch of science. I mean more by this than that there is no royal road to learning, and my meaning extends to this, namely, that there is a great temptation to forsake the steady pursuit of knowledge along the more tedious pathways of careful observation and well-considered induction for the more attractive highways of fashionable theory. I am not alluding now to those whose chief object is to get a reputation for the possession of scientific knowledge careless as to the basis upon which that reputation may rest. It may suffice for such to read a review of them, to plunge hotly into a discussion probably with far more rashness of assertion than they dare to whom the subject had been long familiar. But I speak rather of this danger as besetting those who are sincere in their desire to get to the root of matters. It is a seductive error. It seems so much easier to discuss the merits of a theory than to plod along with the accumulation of facts, forgetting that we are not qualified to judge of the merits of a theory until we have a wide knowledge of the facts upon which it is based. It is that old error of the Aristotelian philosophy which the Baconians corrected. Dialectical skill instead of ascertained facts. Deductions from abstract and a priori propositions made to fit on to nature, instead of inductions from a multitude of observed phenomena leading up to conclusions of high probability. It is not wonderful that, in a population almost entirely occupied with pursuits which afford but little leisure, men should readily take the road which seems to be the shortest to the desired end, but it is a road which subdivides so often that its end is commonly confusion. Mind, I am distinguishing theory from lawful induction, and considering theory as something which men postulate for themselves, and a lawful induction to be a conclusion arrived at from the agreement of so many particulars as to make its value approach that of a general proposition. It is the business of the student of science to acquaint himself with these particulars. It is a common mistake to consider the dealer in theory a philosopher and to stigmatize the work of the plodding student as that of a mere recorder of observations; the former, however, is often a mere empiric, while the latter, if he be not a true philosopher, if he will but persevere is likely to become such because his well-stored mind can hardly fail to arrange his copious data; unbidden thoughts will come and form themselves into conclusions the value of which will be in proportion to his stock of knowledge, his judgment, his mental training, and his mental powers. Only let the philosophy come in its proper place, not first, but last. It will be understood that my remarks have special reference to the physical sciences.

A kindred, yet distinct danger is that of jumping to conclusions upon data, which, if not altogether unreliable, are often very partial. Should the fact or facts in view come in support of an opinion previously formed, some hobby of our own, what an almost irresistible temptation to build a wide-spreading superstructure upon a narrow basis. I

must be forgiven if I hint that this temptation is one into which not a few fall who cannot be said to be very juvenile observers. I will illustrate my meaning from the science of geology. How many imposing arguments we will say as to the duration of man upon the earth have been based upon such calculations as those made in regard to the length of time it would take to accumulate a certain thickness of river deposit over the bone which had been found, or the position of a bone in a bed of gravel. What room there is in such cases for a variety of circumstances not taken into the calculation, but which, nevertheless, may so affect the issue as to render the conclusion almost worthless. Take the former example. There are the considerations which arise from fluctuations in the force of the stream, the climatic conditions, the character of the material deposited, the likelihood of the pre-existence of swamps, etc., and yet we find the number of inches of mud which the observer found to have been deposited within a given time during his own opportunity of enquiry to be taken as the unit of measure; or if we have gravel beds and the like under our notice, especially if the country be a mountainous one, we have to take into the account—not only the even flowing stream we see in years of fair weather, and with its banks protected at all dangerous points by modern appliances to keep the stream to its appointed bounds—but the stream as it was when perhaps lower lying snows swelled its volume as they yielded to the summer sunshine, or primeval forests attracted a more copious rainfall higher up its course. In such cases resistless floods might bring down more material in a few hours than would be accumulated in years under the conditions which now prevail. A night might overwhelm a whole tribe of natives encamped by the stream in a destruction still more dire than that terrible fate which overtook the ill-starred settlers, but a year ago, in their peaceful homes at Motueka, the boasted happy valley. Numbers from Nelson went to be sorry witnesses of what they could not from mere reports believe, viz., that the little river, transformed into a torrent, had torn down from its banks such masses of detritus as to cover fields and gardens in a general ruin, in some instances to the depth of the fences which surrounded them. It might herealter be concluded that the transport of so much material was the work of years.

Another very unreliable class of evidence is that derived from the fossils exhumed from the floors of caves; it is often almost impossible to say how many times these have been disturbed though the appearances may seem to betoken no intrusion. The finding of a broken tobacco pipe under circumstances which appeared indistinguishable from those under which the instruments and ornaments which had belonged to ancient Britons were obtained, was calculated to dispel conclusions which would otherwise have appeared sound. It was bad enough to discover that the tooth, at first fondly taken to be that of a young cave hyæna, was only that of a dog, but the other thing was not to be got over. Now let us suppose that instead of that instrument of vile purpose, which the ancient Britons could never have been so degenerate as to have used, the tooth of Ursus speleus had been turned up, the argument would have been thought undeniable that the ancient inhabitants of Derbyshire—for the cave of which I am speaking is in that county—had to do battle with that extinct animal. I am not saying that there is no evidence for the contemporaneity of the cave-bear with man, but showing how easy it is even for good observers to be deceived. The cave floor may be as completely hardened by the traffic of a multitude of feet within the last few years, during which excursionists have penetrated everywhere, as in a century or so when visits were only paid to such places under pressure of necessity as hiding places in times of trouble. The point upon which I am insisting is that under the inductive system, which is the plan scientists

must follow, matters must be looked at all round before an attempt is made to establish a conclusion. We have to arrive at something like a general proposition from particular ones, instead of the logically more certain process of deducing the particular from a general. The reason of this it is easy to see. In the physical sciences the particular premises are more within our cognizance than the general ones. Thus the two temptations, against which I have presumed to warn students, have their root in the same circumstance. To try to arrive at a scientific conclusion from a general theory is to try to get a certainty out of an uncertainty; and to hastily frame a general proposition out of a small array of observations, even supposing them to be correct enough in themselves, is to make the same mistake by an opposite method. An induction can never do more than justify a reasonable conviction of the mind, and afford the highest probability of the truth of the conclusion, but there is always the possibility of that conclusion being modified by the presentation of further particulars, beforetime unknown or neglected. You see, then, what a multitude of lines ought to converge before a positive assertion is ventured upon—in other words, before this or that is affirmed to be scientific fact. I have alluded, by way of illustration, to the question of the duration of man upon the face of the earth; I then used it in speaking of the quality of evidence, and of the happy knack some have of making a very little go a long way. I press the same question into my service in pointing out how frequently considerations which have an important bearing upon the subject in hand are passed by without fair consideration, possibly from a kind of intuition that they will prove to be lines which will not converge to the conclusion we would fain see established; it is so very hard to be quite unbiassed, and free from all party influences! In debates upon the question I have named, it has never appeared to me that sufficient attention has been given to the enormous possibilities within the period acknowledged by all. I am not now insisting upon the correctness of the most generally-accepted reckonings in Bible chronology, nor am I entering upon the merits of the question I allude to; but speaking of time as an element in such questions, I think that no sufficient recognition is made of all that a thousand years may mean. Realize in mind the condition, say of Britain and Northern Europe generally, 1,000 years ago, with reference to the condition of its population, climate, forests, wild animals, and the like; go back then in mind 1,000 years before that again, and, repeating this process, I think it will be seen that, when enormous periods of time are glibly rolled off the tongue in relation to such questions, there is not unfrequently a failure to apprehend the full force of what is so easily dismissed, and perhaps, after all, it will be thought that the premises which may have been fairly established are not numerous enough, viewed in the light of other considerations, to enable anything like a positive assertion to be made.

I must say a few words upon that alluring snare of over-systematizing in scientific matters. It is so very satisfactory to be able to announce a law; it seems one step more towards reducing confusion to order, it seems to be getting something done and settled; but here again we may be only pushing our particular to a universal. A conclusion in geological science, for example, which is just enough when confined to one locality, is utterly fallacious when stretched out into universality. These remarks will apply, in my estimation, to such artificial arrangements as the division of the human period into the stone, the iron, and the bronze periods. Whatever justification there may be for such a division in a particular country, it cannot consistently with history be predicated in application to the world at large. Every day long-buried trcasures are being brought to light which tell us that as far back as the historic eye can pierce there were nations who had attained a high degree of knowledge and of skill in the working of metals, and if to the testimony derived from the most ancient cities of Assyria or Greece we may