Seeing the call in the February number for "Practical knowledge of hothouse heating," I herewith submit to you my knowledge of the same.

Before I ever thought of horticulture I went to work in a machine shop to get a " practical" knowledge of machinery, and while there learned the use of steam and hot water for heating. Since I have been in this business I have fired personally with the common flues, with the Dick and Meyers hot water boilers, and with Flinn & Emrich steam-heating boiler of Baltimore, and have seen ordinary horizontal boilers used here for steam-heating.

I think that for hothouse heating the hot water system is the best, for when once the water is hot it retains the heat a long time and gives a more even heat than anything else. Second, it cannot get out of order after once properly put up. Third, it does not require a mechanic to run it (which steam does) and there is no danger of explosion, which there is in steam if the person running it does not understand it thoroughly. Fourth, by the time everything is taken into consideration it is the cheapest.

On a very large place where it will pay to keep a man to fire and attend to the heating, who understands all about boilers, pipes, etc., steam can be made to do the work at much less cost than anything else. But if it is not properly put up it will be an everlasting expense and give no satisfaction.

Where one can attend to it himself and understands it it is very good, but where you have to depend on hired help, who very seldom take any i interest in things, and still less often know much I about steam, there is no satisfaction to be had from steam heat.

As to the Questions asked. First: A one-inch pipe is just as good and much cheaper than a larger one, except where the pipes are very long and there is danger of the steam condensing before it reaches the end. Second: Where it takes a five-horse boiler to heat one house it will not require more than an eighteen-horse boiler to heat four such houses. Third: I prefer the radiators to receive the steam from the upper end, as in case of very long radiators the condensed water may interfere with the steam.

It is possible to have steam-heating so arranged with automatic valves that we need only attend to it once in six hours. I have done this myself.