Daily National Intelligencer

PHILOSOPHICAL PRINCIPLES, APPLIED TO USEFUL PURPOSES.

The Editors of the National Intelligencer will probably render some service to the community, by giving the following statements and observations an early insertion in their widely circulating paper.

The unusual degree of cold of this morning, and of the two preceding days, very forcibly admonishes me of a duty which I have owed to the public for some time, but which has hitherto been withheld from an unjustifiable dislike to appearing in the public prints.

It has long been a desideratum with that class of citizens in the middle and more northern states, who are concerned in any kind of mechanical operations that depend on water for the moving power, to be in possession of some easy and effectual plan, for preventing the loss sustained in the destruction of wheels, and the frequent interruptions in business, occasioned by the accumulation of ice on water wheels. It is well known, that, in many instances, it has amounted to a total suspension of all the operations dependant on such wheels for weeks and sometimes months, in succession. In early life, I have often been engaged in the unpleasant task of cutting ice in water-houses, and have frequently assisted in introducing stoves, and sometimes in attending large open fires in those houses; but for want of a scientific knowledge of the subject, they were generally so constructed as to baffle all our endeavors to keep the wheels in motion in very hard winters.

In the spring of 1814, (having suffered great inconvenience from ice the preceding winter, at the Union Factory, where I then lived,) I undertook an investigation of the subject; and, in order that the result may be clearly comprehended, it will be proper to state some philosophical facts, which may not be known by every reader, or owner of water wheels.

The capacity for heat is less in solid bodies than in the same bodies when converted into the fluid state: and less in the fluid than the gaseous form. It follows of course, that gases can only assume the liquid state by parting with a portion of their heat; and that these liquids must still part with a much greater portion before they take the solid form. A familiar instance of this occurs in the slacking of quick lime; in this operation the water combines with the calcareous earth, and thereby assuming the solid form, necessarily parts with a large portion of its heat, which being rapidly evolved, becomes very sensible. The same thing takes place in the phenomenon of freezing: but the operation is generally slow, and under such circumstances, that we do not detect it; but it is ascertained by experiment, that water at 32° of Fahrenheit, must part with at least 142° of temperature before it can be converted into ice at the same temperature, (32°); or in other words, one pound of water at 32 will part with as much heat in freezing as would raise another pound of water from 32° to 74°. These facts being well understood, it led to the conclusion, that if it were possible so to economise the heat thus set at liberty, as to prevent the escape of any part of it, the formation of a very small quantity of ice would so raise the temperature of the air in the room, that it would be absolutely impossible for any more to be formed; but it appeared, on a fair calculation, that if only a small part could be retained, it would effectually answer the desired purpose. This I knew could be effected, by constructing a house of nonconducting materials; and so close as to prevent the circulation of air; but, on the other hand, if it should require an expensive building, it might prove such a drawback on the benefit to be received, as to render the discovery of less importance. This, however, I was well satisfied would not be the case; and I determined to make the experiment the succeeding winter, in the early part of which I took my measures accordingly.

The wheel was about twenty-two feet high and nine wide, enclosed in a stone water-house at the north side of a five story building, and discharged the water to the west; the main building being so much higher, and projecting considerably beyond it at both ends, almost completely excluded the sun from shining on any part of it in short days. It had one door in the east side, one in the north, and a glass window in the west; the whole covered by a shed roof of inch plank. The expenditure to fit it for my experiment did not exceed ten dollars. The north door was closed by a bank of shavings, which happened to be at hand; the fitting of the east door a little improved; the window furnished with a close inside shutter of plank; the joints in the roof closed, and the arch, for the discharge of the water from the wheels, closed by plank down to the surface of the water, and the water swelled by a dam in the tail race, so as to keep it always up to the edge of the plank, when the mill was not in motion, and thereby excluded a current of cold air.

At the commencement of the first very cold weather, care was taken that the water-wheel gudgeon was in good order, and plentifully supplied with tallow, confined by a box, so that it was known it would require no attention for some weeks. The eastern door was then shut and fastened, and orders given for it to remain so until I should direct it to be opened.

The weather was remarkably favorable for the experiment; in a few days the mercury was 12 to 14 below zero, on Fahrenheit's scale, which was colder than it had been for twenty years preceding; about three weeks after, the weather moderated, and I opened the house, and had the satisfaction to find the wheel as free from ice as in a summer's day; nor was there cause to suppose that one pound of ice had formed on the wheel during the whole time; as the mercury was still below the freezing point. A little ice was found on the walls, which being very thick, I did not line with wood, not being willing to incur much expense on the first experiment. Last winter (which it will be recollected was a very cold one) when nearly all the mills in the neighborhood were stopped, our four mill wheels at Triadelphia were completely preserved from ice, by a very slight frame, boarded on both sides in the roughest manner, and filled between with straw, covered with a roof of rough boards and some straw confined on it. Several others have been fitted up on the same principles with uniform success.

I would not be understood to say that water houses never were before constructed so as to prevent ice from accumulating on the wheels. I have seen several, but they were generally more the effect of accident than design. Some men of great experience have indeed discovered that close water houses are more to be relied on for the purpose, than either stoves or south exposures, (though the latter is considered by mill builders a matter of great importance,) yet even these, not being acquainted with the true cause, have seldom or ever adopted the plan best suited to the end.

My object is, to give a rule, whereby the most ignorant may take their measures with certainty, and erect mills any where between James river, in Virginia, and the latitude of Quebec, without ever being stopped one day by ice on the wheels. Let the circulation of air be prevented by the means before stated, or any others that will produce the effect; let the sides and top of the house be composed of good non-conductors, such as a frame boarded on both sides, and filled between with straw, tan, or even shavings, pressed closely in; or, if the house is already built of stone, let it be boarded inside with a single thickness: the roof, water way, &c. attended to as above described, and the business will be effected. But it should always be remembered that the door should never be opened in very freezing weather, if it can be avoided, as the whole air of the room will be thereby changed in a few minutes: the external cold air will rush in at the bottom of the opening, and expel the internal warm air in a strong current at the top.

The investigation of this subject has been amusing to me as well as useful, and I think every person a little dip't in modern science will derive pleasure from the contemplation of it; they will perceive that the positions are such as are now well understood, and the conclusions drawn therefrom, (independent of practical experiment) incontrovertible. Freezing, and the consequent evolution of heat, under the circumstances recommended, may be compared to poison and an effectual antidote operating on a subject at the same time; the very instant the one begins to operate injuriously, it is completely counteracted by the other.

It would be pleasing to know that the scientific enquirer was amused by this investigation; but abundantly more gratifying to be assured that the industrious citizen was substantially benefitted.

T. MOORE.

Brookville, Md., Dec. 22, 1817.