Mr. Editor, - My attention hat just been called to an article in the July number of the Horticulturist, with the above heading, in which the beating apparatus put in for me by Wethered & Cherevoy is so accurately described by your correspondent "B." that I am satisfied beyond doubt that my place is referred to, as there is nothing else in Brooklyn approaching his description. The writer "B." goes on to say, that, though my greenhouses are so loosely built as to do injustice to any mode of heating, (they are substantially built of brick, and nearly new,) yet, nevertheless, the heating arrangements of W. & C. were so satisfactory that I "kept up a high temperature in times that tried men's souls," and that I "said" that when I had trimmed my lamp at night, I had no occasion to look out again till morning. I wish I could endorse this gratuitous "laying" of "B." But the facts are, Mr. Editor, that I was compelled to stay up nightly until midnight in cold weather, while my man had to be on hand at 5 in the morning to keep my plants from freezing, the thermometer being often in one house at 38°, and in the other at 42°.

The gentleman "B." also states the exact quantity of coal burned by me - "eight tons" - from November to May. Another gratuitous assertion, put in to keep up consistency in his "story." How he or any one else could know the exact quantity would be difficult to imagine, as there were three other fires supplied from the same pile. My impression was, that we burned nearly double that quantity; but possibly "B." knows better.

Now, Mr. Editor, the article in question was supplied by your correspondent "B." in response to a call from another correspondent for "facts and figures." What liberties he has taken with the "facts and figures" of the heating apparatus of my place, the above correct statement of the case will show, which, should he attempt to question, let him sign his name, and your readers can then judge between him and James H. Park, Florist, Brooklyn, L. I.

[Very good, James, and outspoken enough; but it only makes the case worse for you, for it is manifest, on your own showing, that you have not read (and probably not seen) the Horticulturist from July to the 6th of November inclusive! No wonder you burn sixteen tons of coal, and have to sit up till midnight freezing at that You know that we have always been your good friend, but it serves you right, James; and we fear we shall not pity you if Jack Frost teases the life out of you the coming winter - unless you read the Horticulturist, in which case we can promise you sound and refreshing sleep, at least so far as your greenhouses are concerned. Never again let any body "call your attention" to what is said in these pages, but resolve from this moment that you will know all for yourself But this between ourselves. Now, "B.," what have you to say in response to Mr. Park's "facts and figures/' which seem seriously to impeach yours, unless he is on the wrong track? - Ed].

More About Boilers #1

Peter B. Mead, Esq. - Dear Sir, - In my article last month read weighting the valve instead of valves. Now to your questions. Probability of blowing up? None. Amount of danger? None. How to avoid it? "First catch your hare." In regard to capacity? Can not say, the one I have in use being a small one for heating a forcing bed, and not a green-house; at a guess should say that, where a four-inch pipe is used, a one and a half or two inch Would answer. In regard to detail, do not think there is any more to give; almost any machinist will get up one from the sketch.

A word of explanation of action may be necessary for those not familiar with such things. The apparatus being filled, (the regulating valve having been lifted to let out the air,) valve weighted at desired point, and fire started, the water expanding with the heat, the surplus amount is forced through the valve, and runs away, or into the feed tank, as shown, leaving the proper amount in to work at the pressure fixed upon. After this discharge, if more fire is made than is necessary to keep the water at that point, it runs over again, which must be stopped, either by increasing the pressure, or damping the fire, until you hold it at the desired temperature, just below the blowing-off - not "up" - point. It is least trouble, though, and saves water, to put on the full weight -at once, and blaze away; damping the fire when your house gets too hot. Nervous individuals, however, who are frightened at the mention of hundred pounds' pressure, can regulate it to suit their pulse. When the fire is let down, or cleaned out, the pressure being taken off the check valve or feed pipe, the water in the feed tank runs in, and fills the machine up again.

If the fire be kept up, so that the pressure on the check valve from the furnace is never less than that on it from the feed tank, (which, of course, depends upon the height at which it is placed, depth, etc.,) it is not necessary that a single drop of water go in or out after once fairly at work; but to insure a proper circulation at all temperatures, the cistern should be kept filled, so that the machine can fill itself when necessary.

In the event of steam being raised, which can only happen from the grossest negligence - firing up and not weighting the valve, and running the water out - no harm will arise; only the trouble of letting down the fire to get in the water. If all the water were out, and the thing red hot, it might not be pleasant for "my man" if he poured any in; though I am not certain that.even in this case he would get his desert Where water-works exist, all trouble of tending the cistern is removed, by attaching the feed pipe to them; the regulating valva must be kept weighted at a greater pressure than the head of water, or, in the event of the fire being let down, it will keep running through.

If any thing more is written on this subject, it had certainly better be, as you say, "divested of all personal considerations whatever." When I penned my last article, I had no idea that B. was writing up, or P. down, a particular make of furnace; I do not think I noticed whose Mr. Park's was. To suppose that any apparatus of the proper size will not warm a house is simply ridiculous; of course there is a choice of furnaces, or boilers; the most important point being, I should think, to have it large enough to hold fire for ten hours. Whether this or that one will evolve more heat with the same fuel can only be determined as you suggest, by working first one and then the other, in the same house, and making accurate thermometries! observations, out and inside; the variations of the force, and the direction of the wind, will prevent even such experiments from showing exactly correct results.

Mr. Chorlton no doubt hits the nail on the head, when he says Mr. Park's apparatus is too small, as by data given he evidently knows what he is talking about; this is re-"confirming the opinion I formed," (jumped at, having no experience in the matter,) which is all I meant to convey; that is, it is too small sometimes - in zero weather like last Sunday - and here lies the advantage I claim for the wrought-iron, high-pressure apparatus: that it can, when necessary, be forced to do double or treble the ordinary required duty.

The error at Mr. Park's probably arose through miscalculations on the part of the makers, or mistaken economy on the part of the purchaser. I would remark, en passant, that he loses considerable heat by carrying his smoke pipe directly away outside.

I think Mr. Chorlton and others are behind the age in the affection they exhibit for cast iron - it is becoming considered a very mean material, only fit to be used where ballast is required.

Jan. 21,1861. Brooklyn.

[We concede "the hare" to you, but can not consent to let you reduce the bore of your four-inch pipe to any other whatever; that would be a great mistake. Our object was to give, you a chance to say something bearing on the prevalent prejudice against high-pressure " machines" of all kinds. Though you do not think there are any more details to give, you have notwithstanding furnished just the details our readers want, and for which we thank you. It would certainly be difficult to "blow up" your boiler, except, as you say, through gross carelessness. We shall take an early opportunity to see it in operation. - Ed].