the localization of sensation is often vague in the extreme, but it is difficult to imagine an unlocalized sensation. Now this localizing of sensation is a characteristic feature of perception, a localization, which, it should be observed, is due not to some ready-formed extra-mental attribute, but to the mind's own energy. Were we only passive our sensations would only have intensive, but not extensive quantity; we might discriminate difference of degree of feeling, acuteness and massiveness of sensation, but we should not spread out these sensations into a continuum, not assign them a relation of co-adjacence as well as of co-intension.

The life of perception is more or less immediate or concrete. Although the actual basis of subjective affection may be smail, the experience is essentially real, and although the additions from ideal memory may be considerable, we are warranted in regarding the perceiving attitude as the attitude of reality par excellence. But when the stimulus is removed we drop from the public sphere of reality, and are left in the realm of private ideality. A man's perceptions are not his alone; in possessing them he participates in a common life; but a man's memories and thoughts are his and his alone. The vivid percept is first degraded to the faint image, and the image finally loses all form and colour in the idea.

Another expression for this sequence of events is that conscious life consists in a passage from the concrete to the abstract. The primary experience exhibits the maximum of concreteness. The world of the young child is a world of actual vivid feeling, absolutely articulated, a robe of perception without a seam. As some of the causes of its impression are uniformly withdrawn it finds a difference of colouring in its experience, and learns to distinguish between the objects actually present and the paler surviving relics of its memory. By transposition of stimuli, moreover, the fixity of primary association is infringed, and the youthful mind learns to partition its experience, and to form a more precise representation of the world of things.

The multiplication of experiences does something more than this, however; it makes the retention of images more and more difficult, and the necessity of keeping pace with a world in such constant flux and progress reduces the major part of these images into signs. The process here alluded to is the mental attribute termed Abstraction, and the ability to perform such an act indicates an immense advance in intellectual power.

But now, did the control of conscious experience end there it would never have been possible to define man as animal rationale; for rationality implies operation not on particular, but on general signs, and to effect that an instrument must be constructed which shall facilitate representative knowledge, which shall not only enable the mind to perceive a lion from a certain odour or colour, but allow the mind in its solitude to think lion, as in the unspoken judgment 'lions are dangerous beasts,' without any concrete reminder, either through the medium of the sense-organ or the internal organ of imagination.

For thought, for reasoning, we require a mental algebra, and the quantities of this algebra are termed Conceptions. The concept is related to the percept as the a's and b's of common algebra to the pebbles and other discrete objects of daily experience. By its aid the single rational intuition may do duty for number

less sensible intuitions, and we can carry on a train of thought that without such a symbolic language. would have been impossible.

From the system of sense to the system of thought we creep thus gradually. To us of the present day the chasm seems inconceivably vast between the prevailing life of perception of the brute and the prevailing life of conception of the civilised man, but the gulf may not really be so great as it seems. The missing link -the origin of language-will doubtless be detected. by the penetrating eye of future science.

The civilised child, as standing nearer to the primitive age of the race, leads a life still largely percep tional. To try and force the youthful mind beyond its constitutional capacity to the higher stages is both vain and injurious. A premature absorption in reflection and abstraction not only atrophies the body, but also engenders a barren schematism, in which the mind spends precious time in the fruitless working of a new instrument, without the application to material, for which the instrument is alone desirable. But as time goes on, the operations on signs rather than on the things signified must make up a large part of the doings of consciousness, and judging and reasoning be the daily portion.

cesses.

Very early indeed the habit is formed of striving to enlarge the area of experience by purely rational pro Uneducated and educated alike are prone to make universal assertions on the strength of a very slender amount of evidence, the practical utility of an 'all' giving, doubtless, the cue to this usually erroneous extension of the known. If we are to believe the school books, the counter process is even more common, of pushing the vast stock of supposed general truths, whether derived from tradition or through the operation just described, into all their consequences. But I take leave to doubt whether this 'deductive' operation, as it is technically termed, is really as general as our logical teachers would give us to understand. The actual state of the case seems to be far rather that alleged by J. S. Mill, when he maintains that the primitive and common mode of inference is from particulars to particulars on the ground of superficial resemblances. We induce or make general assertions on the strength of a few instances fast enough; but we rarely deduce, or reason downwards from assumed general principles, unless our vocation lie, as with the judge or the mathematical physicist, especially in this direction.

The performance of the intellectual operations of which mention has been made is never unmotived, although the motive may not always be self-evident or even conscious. Will, as I hinted above, is, in my opinion, not synonymous with volition, the former being a genus, of which the latter is a species. A volition I define as an act of the mind, determined by a motive distinctly presented to consciousness, and a large number of our activities, although plainly mental or subjective, do not possess these consciously realized antecedents. While, then, in the case of many centrally-initiated activities it is hard to say why and how they arise, when once they are set on foot, and generate associations and intellectual combinations, of various orders, they are either continued in vir ue of something else than their own momentum, or retarded by another cause than their own inertia. All acts of the mind are with rare exceptions accompanied by a conscious ingredient termed pleasure or pain.

They either cause delight or occasion a sense of displeasure. The exceptional cases are when the physical or psychical stimulus is, in relation to the excitability of the system, of so limited an amount as to arouse the mind from its torpor and nothing more, or when by long action of the stimulus, the mind has grown accustomed to the new condition, an increment or decrement of stimulus being required to change its

tone.

When the pleasure or the pain is detached from its intellectual surroundings, and made a distinct object. by consciousness, volition occurs, and we are said to work for a specific end. What ends we should work for, and what motives to the will we should suppress by a counter effort, in view of a still greater good, is the problem of the discipline of the will-a subject of supreme importance, which will subsequently require a paper to itself.

I will here only make the psycho

logical observation that the work of volition must not be judged by the complexity of the impelling motives. It is not the circumstance of deliberation and resulting resolution that is the characteristic mark of a voluntary act, but the initiating of movement itself. Whether the motives be one or a hundred, will is always there when the mind is strained to effect a certain purpose.

The conflict of motives just alluded to, however, introduces us to the circumstance hitherto passed by in silence, that the mind is often the theatre of intense struggle; that, indeed, as the tendency to regard volition as emerging from conflict shows, it is an internal sea, where perfect calm is rather the exception than the rule, and violent storms alternate with gentle breezes. The definition of man as animal rationale is indeed partial in the extreme. The emotions are not the least permanent or least important part of our mental constitution, and the culture of the emotions presents even a more difficult problem than that of the intellect. A wrong heart is at least as mischievous as a wrong head, and there is not a little danger that in our anxiety to avoid the intellectual aberrations of our ancestors, and to make the mind a better mirror of the rational order than heretofore, we may leave to chance the training of the instinctive feelings, and the social sympathies, and so let the tares of lawless impulse choke the wheat of knowledge we have so sedulously sown. If the motive of intellectual veracity obtain by strenuous habit complete sway over the wandering trains of thought and a too eager imagination, the mind will be still ill-prepared for encountering the real stress of actual life, unless the motive of moral veracity, and a strict regard to the legitimate feelings and rights of others, constrain individual action to a perfect harmony with social needs and endeavours.

The contents and purport of this introduction may be thus briefly summarised. The education of youth, to be successful, that is, to fit the child to play a worthy part in after-life, must be in obedience to the laws of mind. A complete understanding of these laws would require a thorough knowledge of the antecedents of the particular mind. Such antecedents are and always will be for the most part unknown. The most we can hope for is to understand the general workings of the mind, assuming a uniformity of operation under approximately uniform conditions. The teacher will, however, as far as circumstances permit, carefully note deviations from the normal type, and vary his prac

tical rules in accordance with the peculiarities of the case. The business of the psychologist is to trace out the statics and dynamics of a typical human mind, to resolve compound mental operations into their proximate and ultimate elements, and to explain the mechanism by which mental results are obtained. The practical teacher will accept these theoretical inductions and deductions from the hands of psychologists, and will be guided by them in practice, possibly repaying the debt by collecting fresh facts for the elucidation of the theorist, the favourable opportunity possessed by him of witnessing the development of minds from a comparatively early age having as yet been hardly sufficiently utilised.

The maxim which has been found so fruitful in other departments will bear excellent fruit here likewise: Follow nature,' understanding by nature in the present instance those co existences and sequences which have been established by the psycho-physical adhesive growths of centuries, which we may modify, but cannot undo.

in the one large cork with which you fit the mouth of the flask. As one hole is to be traversed by a thistle-funnel, and the other by a piece of glass tubing, use cork-borers a little less in diameter than the tube of the thistle-funnel and the glass tubing respectively. Wet the borer, and push and turn it at the same time; beginning at the small end of the cork. Pass through one cork the thistlefunnel, after wetting or greasing it. Here also push and

twist simultaneously. Let the funnel tube go through the cork to such a length, that it will nearly reach the bottom of the bottle. Before introducing the glass tubing into the other cork, the tubing must be bent as in the figure, or bent twice; once at right angles at a point that will afterwards be near the cork, once at an obtuse angle at a point some 6 or 8 inches from the cork. To cut the piece of tubing off from a length of tubing, a notch is made with a file in the glass, by drawing the file, not too vigorously, across it, until it has eaten into the glass. The cut may be extended in a circle round the tubing, and then the latter being laid on the thumbs and over-grasped by the fingers, the cut lying between the two forefingers, pressure with the thumbs, and

Fig. 3.

gentle drawing with the hands to right and left, cause the tube to break with a clean fracture. If the edges are not quite smooth, heat them in the flame of a Bunsen burner (Fig. 3), directed upon the glass by aid of a blow-pipe (Fig. 4).

Fig. 4.

To bend the glass tubing. Hold it in the upper part of the flame of a batwing gas-burner, a burner with a long narrow aperture, turning it round and round. When the glass softens, bend it steadily but slowly at the required angle, after removing it from the flame.

Introduce one end of the piece of glass-tubing that has been bent twice, once at a right angle and once at an obtuse angle, into the other cork, or pass it through the second hole in the single large cork. Let it only just pass into the bottle. To the other end of this delivery-tube attach a piece of india-rubber tubing, and to the remote end of the latter a piece of glass tubing bent upwards at

its free end.

Partially fill a pneumatic trough with water, and place in the water a bee-hive or hollow cylinder of earthenware, with a hole in the top, and with part of one side cut away (Fig. 5.) Fill with water several gas-jars, and

Fig. 5.

invert them in the trough, taking care that no air enters, no water escapes. Let the end of the delivery-tube pass into the bee hive through the cut-away side-wall.

Place in the bottle some granulated zinc. Pour through the funnel enough water to cover the zinc and the lower open mouth of the thistle-funnel. Then add sulphuric acid (hydrogen sulphate) through the same channel, taking care that the proportion of water to acid is about 12 to 1. The zinc is dissolved by the acid and takes the place of the hydrogen, forming a salt, zinc sulphate, that is left in solution within the bottle. The hydrogen gas thus displaced escapes through the delivery-tube, and after expel

ling the air from the bottle, rises through the water in the trough and escapes at the opening in the top of the bee-hive. When you judge that all the air has been expelled, and that hydrogen is now bubbling off, pass a gas-jar on to the bee-hive, letting no water escape, and allow the gas to displace the water in the gas-jar. When the jar is full of gas and empty of water, pass it from the bee-hive on to a plate-glass plate that serves to close the lower open mouth, and remove the jar filled with hydrogen from the water. It should be kept mouth downwards. Catch three or four jars' full in this way, and then catch one or two by displacement of air, holding the jars mouth downwards, and closing each jar when you think it is full of hydrogen, with the glass plate.

The zinc used in this experiment must not be pure zinc. Upon pure zinc the action of sulphuric acid is nil, unless a drop or two of a solution of some lead or copper salt is placed in the vessel. Then, as the zinc is rendered impure, action takes place, and hydrogen is evolved.

In this preparation, zinc and hydrogen sulphate become hydrogen and zinc sulphate.

(2) Symbols.-Zn + H3SO1 = H2 + ZnSO4. Zn stands for the metal zinc: H2SO4 for the hydrogen sulphate or sulphuric acid, which consists of two atoms of hydrogen, one of sulphur, four of oxygen. H2 represents the hydrogen that passes off: ZnSO4 the zinc sulphate left in the bottle, and made up of one atom of zinc, one of sulphur, four of oxygen.

(3) Weights and Volumes.-Zn has weight-number 65 approximately (see table in last number, p. 12). H=1, S=32, O=16. Hence= H2 + ZnSO1,

65+

Zn + H2SO4 (2+32+64) 98

2+

(65+32+64) 161

i.e., 65 parts by weight of zinc, treated with ninety-eight parts by weight of hydrogen sulphate, yield 2 parts by weight of hydrogen and 161 parts by weight of zinc sulphate.

Volume has only reference to bodies in the gaseous condition, and in this experiment hydrogen is the only gas concerned. H2 represents two atoms or two volumes.

We are already using the words weight, volume, atom. Let us once for all make clear the meaning of these words.

The system of weights and measures used by all scientific workers is the metric system. Its unit of length is the metre, a ten-millionth part of a quadrant of the earth's meridian. In English measures the metre is 39'37 inches 3.281 feet or a little more than a yard. The metre is divided into tenths, hundredths, thousandths. The metre is grouped up into multiples of ten, of one hundred, of a thousand metres. The sub-multiples are named from the Latin words decem = ten, centum=one hundred, mille a thousand, respectively decimetre (1% of a metre), centimetre (r of a metre), millimetre (ro of a metre). The multiples are named from the Greek words deкa (deka) = ten, éxаTOV (hecaton) = a hundred, xo (chilioi) = =a thousand, respectively decametre (10 metres), hectometre (100 metres), kilometre (1000 metres).

The unit of volume is the litre. This is a cubic decimetre, ie, 1000 cubic centimetres (103=1000). Its English equivalent is 1765 imperial pints, or 6103 cubic inches. This, on the same principle as that used in dealing with the metre, may be divided into decilitres, centilitres, millilitres, and grouped up into deca- hecto-kilolitres.

The unit of mass, or quantity of matter, and of weight, is the gram. This is the mass or weight of a cubic centimetre of distilled water at a temperature of 4°C, and under a pressure equivalent to that of a column of mercury 760 millimetres in height. Its English equivalent is 15432 grains. This is divided into decigrams, centigrams, milligrams, and is grouped up into decagrams, hectograms, kilograms.

(To be continued.)