IF the present exceptionally high, price of coal continues, will it affect injuriously the development and progress of the forcing or hothouse department of Horticulture? This is a question which is being considered at present with considerable misgiving. That it will exercise a considerable influence on the owners of gardens, as to whether they shall expand their glass-houses, or make a beginning in the case of those who have not yet embarked in the production of tender fruits and flowers, is beyond any doubt. In many localities coal is at present nearly, if not quite in some instances, two hundred per cent higher in price than it was three or four years ago. Nor is coal the only agent at present indispensable in hothouse heating that has advanced in price. Coal is only the heat-generating agent. Iron forms the highway by which it is carried and distributed to the atmosphere of our plant and fruit houses; and iron, too - always an important item in hothouse erections - is now well-nigh 100 per cent dearer than it was two or three years ago.

Here, then, we stand face to face with two articles - to say nothing of others - on which this important branch of gardening is, it may be said, solely dependent, enormously enhanced in cost ; and it would be folly to doubt that, in consequence, fewer Orchid-houses, Graperies, and Pineries will be erected, unless some means of great economy in heat crops up to counterbalance the present state of things, which it is to be feared may last for a considerable time.

We do not require to look far afield or study profoundly to see that there is a waste of heat going, and apparently to be allowed to go, on with the greatest complacency in this country, first, in nearly every dwelling-house in the kingdom, to an extent which, when it comes to be considered, is barely worthy of the rudest barbarism. Most certainly, if such a deliberate waste was perpetrated in connection with any other necessary of life, it would not be too much to look or call for Government interference to prevent it. By way of pretending to heat our living rooms and cook our food, architects persist in making a recess in one corner of our rooms, in which to burn coal by the hundredweight; and which is effectual in no earthly way, unless it be that of sending the whole, or nearly the whole, heat up a chimney, to serve no purpose more sensible than that of being a nuisance to all animal and vegetable life outside our dwellings; unless, indeed, it be the still more undesirable one of creating draughts of cold air inside, and rheumatics and colds to boot.

This is one of the most deplorably outrageous wastes of an expensive necessary of life that ever characterised any age or nation worthy of being ranked among the scientific and civilised. "We do not think it is too much to say that there is as much heat wasted in Glasgow as would heat every dwelling and hothouse in Scotland, or as much wasted in London as would go a long way towards keeping every shivering limb in England warm and comfortable if it were properly applied.

But turning to Horticulture, with which we have at present to do, it cannot be said certainly that the waste is so deplorable as in the case of our living-rooms and kitchens. Indeed, if gardeners heated hothouses in so dirty, unhealthy, and wasteful a manner as their living rooms are heated, it would take twenty fires for one that is used in connection with horticulture. Perhaps it may, however, be justly said that, as we heat by hot water travelling in iron pipes, a certain and considerable amount of waste is unavoidable. It may be difficult to dispute this; but surely horticultural engineering and genius are not so fully exhausted as to be bound for ever to water and pipes of iron, which, in spite of dampers and the most ingenious boilers yet invented, only catch or absorb part of the heat generated by coal; the rest is so far wasted in passing into space by the very " short cut" of chimneys.

Our present object is to appeal to our horticultural engineers and Royal Societies for assistance. Can they do nothing more, nothing as good, and yet much cheaper, in the way of heating the air of our hothouses, than exists just now in the shape of expensive boilers, tons of bricks and iron, and water? Never before was economy of heat so urgent in the history of British gardens, at least not since railroads were invented. Coal is now a serious item to encounter in erecting and working hothouses. The waste of it is perhaps the most serious part of it all. Are we to suppose that efficiency and economy in hothouse heating have reached their climax 1 We should be sorry to think so. If the grimy sons of the pit cannot be superseded, or aided so far by means of machinery to cheapen the coal, can we not hope for relief to come from an improved system of applied heat? We do not know of anything that would at present give a greater momentum to Horticulture as a greatly lessened cost for coal: whoever can happily hit upon any means of doing this his fortune would be certain.

Cannot any system be invented by which we can more directly heat the atmosphere of hothouses without so much costly iron, such immense bodies of water, and such an escape of heat up our chimneys 1 Who will say that there is not, if it could only be found, as the sculptor finds his ideal figure in a block of marble 1 We are under impression that there is a road to this desired end, and that it lies more by way of heated air than heated water and expensive water-ways.

An inventor of an apparatus called on us the other day with models on his way to the Patent Office, which invention he has proved, in heating a range of hothouses, supplies the heat for nothing; or rather it produces so much of another material in the process of heating as clears all cost. We hope soon to be able to refer to the particulars of this process, which will be applicable to many districts in Britain, though not to all. We know that others are at present deeply engrossed in solving the hot-air principle, and to these, and all others that will so far effect the end, every well-wisher of Horticulture must wish good speed. A correspondent hailing from the Scotch oil district favoured us with a communication some time ago on economic heating, and promised to refer in our pages to the matter again; we should be glad, and no doubt so would our readers, if he would redeem his promise.