know why and how he is to depart from it. Thus, in a course of Natural Philosophy or Physics, 'Dew' is explained, under Heat, which subject is preceded in the course by Dynamics, Hydrostatics, and Pneumatics. A wide basis of physical knowledge has thus been laid in the mind of the regular student; in particular the laws of motion, and the law of gravity, have been applied fully to solids, liquids, and gases; while, in the subject of Heat, where Dew comes in, some of the leading facts have been expounded, as the expansion of bodies, liquefaction, and vaporization, and their opposites, with the doctrine of latent heat. Stored with all these preparatory explanations, the regular student of Physics is introduced to the topic of Dew; and the teacher still finds a good deal to say before it is completely mastered by a youth of average intelligence. Taking all this into account, we should naturally despair of bringing before pupils of ten a subject that fairly tasks the powers and the acquired knowledge of a pupil of sixteen. Such would be our first thoughts. The second and better thoughts are to consider what limitations, omissions, precautions, the altered circumstances impose upon such a lesson. We begin by stating to ourselves the reasons for making the attempt at all; namely, to engage the attention of the young mind with the facts, appearances, and operations of the world, so as to have some impressions that the regular teacher can afterwards work upon; for the professor of Physics, in his lecture on Dew, would be very much at a disadvantage with pupils that had never even noticed the wetness of the grass on a morning after a clear and rainless night. We next recall the circumstance, that cause and effect, in some form or other. EXAMPLE OF DEW. 269 is noticeable by and intelligible to the youngest capacity, and even seizes hold of the attention of its own accord; nay, more, that the youngest mind will form an induction to itself of the conditions of any startling change. Every child is a self-taught natural philosopher in such matters as the fall of rain, the wetting of the ground and the filling of the water channels; and will reason, from the occurrence of wetness and rushing streams, that rain has just fallen. To guide, rectify, direct and forward this spontaneous observation and reasoning is the purpose of the teacher in the lessons that we are now considering; with the serious drawback, however, that the perfect form of the truths cannot yet be imparted; and that, on the way to the perfect form, the pupil has to pass through several forms that are imperfect. Before applying these reflections to the case of Dew, the remark is significant and helpful, that a century ago Dew was not understood at all; until Black had expounded latent heat, and Dalton studied the constitution of the steam atmosphere, no satisfactory account could be given of the phenomenon. Still it was not entirely unknown, and such knowledge as was possessed was correct and useful. This shows us that there are forms of knowledge, short of the highest, that yet possess value. That former knowledge of Dew was empirical knowledge; and the knowledge that we give to children in advance of the perfect form we have designated empirical too. It is so, however, not by the necessity of the case, as it was to our fathers, but by deliberate and artificial shaping on our part. We know the real solution, the rational explanation; but we withhold it as premature. Yet, here is the advantage of our position; we can use our full knowledge to improve the empirical statement, to make it less removed from fact, and more full and intelligible for its immediate purpose. We can let drop forecasting hints as to what the pupil will one day fully understand; we can even tell the real cause in a general way, while we cannot point out all the steps. It does no harm to complete the empirical account of the Tides by the indication that they are due to the united attraction of the Sun and the Moon; our error is to attempt to show this in the detail to pupils that are incapable of abstract dynamical conceptions. We can give them a very valuable lesson without an overvaulting and premature attack upon the citadel. We engage attention and observation upon a great terrestrial fact, we plant a large conception in the mind, we give a proximate explanation of a phenomenon of perpetual occurrence; we sum up in a generality a host of scattered appearances: we are thereby justified in putting forward the subject as a knowledge lesson in advance of the pupil's attendance in the Natural Philosophy class room. To resume the example of Dew. While the lesson is avowedly given to those that cannot understand the reasons or explanations, and, therefore, does not presuppose all the knowledge that should properly go before, it still needs some previous preparation of mind, and must take shape according to the supposed knowledge of the class. It ought not to be given without certain other lessons; such as, the materiality of the atmosphere; the three states of matter as depending on heat- a very good example of an empirical lesson; the boiling of EXAMPLE OF DEW. 271 water; the difference between gaseous water proper and visible vapour or steam; the drying up of wet surfaces, and of ponds of water; the heating of the air by the heat of the day, and its cooling at night. Such points being premised, the lesson might assume this form: - Water, when disappearing by drying, becomes a gas diffused in the atmosphere. The atmosphere does not hold above a certain quantity. What is the consequence? Either the drying must stop, or it must be thrown down again to the earth. It is thrown down in the form of water as rain. This is the chief mode of returning to the earth. Before it appears as rain, it exists as clouds, which feed the rain. Rain comes when the air is cooled by the vicissitudes of day and night, and by changes in the wind; the great fact is coldness. We can obtain water from air in various ways, if we cool it enough. The ground becomes cold at night, and the surface is wetted, although there has been no rain. The sum and substance of the lesson would be to connect drying with the heat of the air, and the return to water with its cooling; to impress which in broad general terms would be quite as much as could be done in one lesson. Obviously, the rain and cloud lesson should precede the lesson on Dew, which is an exceedingly subtle consequence of the general fact. The reasons why dew is absent altogether on some nights, and why in one night some bodies are dewed and others not, cannot be imparted intelligibly without a distinct lesson. The statements might be given as empirical facts, that grass and wool are more liable to be dewed than stone and metal; but the theory of sur face radiation and of its differences in different bodies should not be foisted in for the first time in a Dew lesson; either it should have occurred in a previous lesson, or it ought to be entirely withheld, leaving only the empirical statement. It is the very essence of the Object Lesson to be empirical. In an Appendix note, the niceties of the lesson in Primary Science are further brought out by a critical review of some select examples. To this is added a discussion of the forms assumed by the Lesson as arising in the explanation of words that occur in the reading books. Geography. The aims of Geography are very well-defined. The conception of occupied space is its foundation; it is the all-embracing framework of the outer world in its orderly arrangement. On the great scale, it gives a place to everything, and peoples every place. It is the greatest task of the pure conceptive power, in its literal or matterof-fact working, as opposed to the imaginative or emotion prompted working; this alone would make it a late study, as the child has but little concrete conceptive faculty, and that little is disturbed by the intrusion of strong emotional effects. A long series of lessons on the isolated objects of the outer world-implements of utility, minerals, plants, and animals-serve as part preparation for the vast geographical field; but that field opens up an entirely new exercise of the conceiving power, which must be grounded on a distinct line of observation and experience. The simplest objects of Geography-hills, rivers, plains, |