J. H. P., of Vt.—You will find Prof, Wright correct when you make careful experiments. Not being acquainted with your plan, we could not give you an answer. J. G-. J., of 111.—It is a mistake which we have often Eeen made, to suppose that one part of a machine rotating, but to work in combination with another main part having a reciprocating motion, does its work quicker than a machine wholly reciprocating. Your platten has a reciprocating motion, and your cylinder 'cannot be made to work faster than it. Your press3 however, appears t o be a good one ; but you know that many mechanical combinations really require experiments to determine their superiority; some combinations, however, are so plain that we can at once point out their virtues or defects. A. 0 , of Conn.—It is our opinion that your boiler is a good one; we judge this by your description and sketch, the latter being very imperfect. A model should be made as soon as possible. The Air Condenser will not answer; air is not a suitable medium for taking up the heat rapidly j it is a bad conduc* tor. J,P., of Miss.—Your letter asking information about Camp's invention is received, we cannot furnish any information respecting it not found in the Sei. Am , to which you refer, therefore we have passed the $1 to your credit on account of subscription. A. W. Z , of N. Y.—For taking photographs on glass, a solution of gun cotton, called collodion, is employed. R. M , of Me.—It is a mooted point whether there is such a substance as ozone in the air, or whether it is only oxygen modified or changed by electricity. W. B. S., of Ga.—A substitute for the American cotton gin haa been attempted in the East Indies, but has not succeeded. The English East India Co" have offered a large reward for an improved cotton gin that will suit cotton grown in the East Indies, for which the one now in use is not altogether suitable. B. B., of La.—A centrifugal refrigerator lias been lately patented in England. B S. T , of Me —"Hydrated" signifies coataining moisture, and "anhydrated" deprived of the same. W. L., of N. H,—Sulphuric acid and oil of vitriol are the same. I. M P., of Tenn.—We do not think your plan will interfere with, any other in use ; so far as we understand it the plan seemsto be good. W. S., of Me,—Wethink your device possesses novelty sufficiently to warrant an application for Letters Patent. You had better fiend us a model. W. MeB., of Ohio—The sketch of your (- Choir Time Keeper " baa been carefully examined, and is believed to possess novelty of a,patentaMe character. We apprehend, however, that a patent would be of little or no pecuniary value, We see little in it which is valuable as an article of merchandise. J. C. C., of Ind.—All right, L, D H of Vt—We think if you should use the I flre box and chimney you would infringe one of the patents issued, but perhaps not the one referred to by you. -i. B., of Sehenectady—As yet we have had no tidings from the Patent Office, concerning your case siace the papers and model wero acknowledged. Hope to hear soon : should think it was time it had beeu examined. M. C. B., of Ohio—The plan you offer as a substitute for the crank is eld and useless; it has been j re invented hundreds of times, and we have now in our office several models of it. T,,of N. Y.—The glass is French; we have Been no other. Cannot you get the chemicals pure from E. N. Kent, in John street ? We believe you can. You are right about the Hillotype, but it would not do to use such strong language as you do. J. S , of Ky.—Yours will receive its place. H, S. H,, of N. Y —When an individual advertises the sale of a valuable invention as low as a dollar, for a right to use it, we are apprehensive there is aome humbug about it, and don't like to be accessory to such schemes by insertingtheiradvertisements in the Scientific American, The money you sent us is subjectto your order. E. Van C, of Pa.—You are at liberty to introduce your invention on any of the railroads that will adopt it. Engravings of your apparatus would cost $15; no charge made for publishing. P. D.j of Pa.—We have no desire to publish your article, others beside yourself entertain the opi nion that light is a subtle matter, and we must say, that we have seen the subject more ingeniously treated. 0. Y., of N. Y.—0. B. T.'s claim could not extend farther than its application to the felt for the specific purpose mentioned, or any like purpose that he could certainly claim. L. L, M,, of N. C—The undulatory theory, or that light moves in waves, has been very ingeniously propounded by Fresnel, a French writer on the subject. M A.,ofN. H.—By the wheel and axle any one continued rectilinear motion may be made to produce another in any other direction, and with any other velocity. S,W. T., of S. C—The place to be assigned to a fly wheel relatively to the other parts of the machinery is determined for the purpose for which it ia used. B. A., of Ala.—By the term "latent heat," is meant that which is insensible to the touch, or can-i not be discovered by the thermometer. B. W., of Mass.—The theory of mechanics \S founded upon mathematical science, and consequently a knowledge of geometry is necessary to understand it thoroughly. E. L. T., of S. C—Bodies that radiate ceafbest, j likewise absorb it best. ' A. M., of Miss.—Wintergreen grows abundantly in some parts of New Jersey, its extract is highly esteemed for many purposes. S. P., of N. Y.—We do not know of a wood.planing machine like yours, but the same principle is embraced in Eayrs' atone dressing machine published in our last volume. R. I., of Va— Wo do not know the plow by the name mentioned. You had better offer something, say $50, for the best plan for a farnace—we know of no one who would undertake it, although there are many. B. L. W., of Miss.—The beat writer to consult on the application of manures ia Sir H.Davy, in his Agricultural Chemistry. Money received on account of Patent Office business for the week ending Saturday, Jan. 15 : W. K., of Mass., $15; G. R., of N. Y., $35; J. O., of Ct, $20 ; W. S. P.. of Ci, $30 ; W. M. W., ofCfc, $20; G. N. L. D., of N. Y., $20 ; B. B., of N. Y., $30 ; F. O. L., of Pa , $30 ; J, B, T., of N. Y., $25 ; I. H., of O., $45 ; G B. S , of N. Y., $25 , C. amp; R., of Mass., $25; F J. T,, of N. Y., $20 ; A. C, of N. Y., $35. Specifications and drawings belonging to parties with the following initials have been forwarded to the Patent Office during the week ending Saturday, Jan. 15: W. P., of Mo.; G. N. TJ. D , of N. Y.; J. B. T., of N. Y.; A. C, of N. Y.; I. H., of O.; G. B. S-, of N, Y.; P. J. T,, of N. Y. ; C. amp; R., of Mass.