R. H., of Me.-It is not new to insert the plumb and level in a trysquare. It has been done before. \Y. R. H., of rrexas.We are not acquninted with Professor Forshey's paper on Texan northers, but if you caD give us any particulars of it, with your own remarks, we shall be happy to receive them, as we should like some information on the subject. F. G. L., of Ala.It is a well-known fact that a line disposed in the form of a circle will enclose more space than any other form. E. F. W., of Ga.Writing machines have long been talked and thonght of, and patent was taken out a few weeks ago for a key printing machine, which would nearly answer your description and ideas. J. T., of Texas.The idea you suggest of throwing a jet of steam direct from the boiler into a casing around the barrel of the locomotive pump, so as to prevent freczing, is not new. The same thing has been proposed to tIS before. S. W. R.. of Vt.The advantage of what is termed " snperheating" steam, that is to say, heating it after it has left the boller, when only carried out to such a degroe as to vaporize all the globules of water which it has carried with it from the uoiler, and thus render it anhydrous is universally conceded. Many arrangements of superheating pipes have been employed for this purpose, sometimes in the main fire-box and sometimes in the flues or chimney; but there has been a great difficulty in controlling the temperature of the superheating pipes, so that they should neither burn out or cause the steam to ue superheated to excess, both of which results are very likely to occur if the pipes are placed in the main fire-box. If you can arrange your pipes in snch a manner as to guard against their being overheated, you will obtain a considerable advantage by " superheating." J. M. T., of Ind.We are obliged to inform you that there is nothing new or patentable in your alleged improvement in water wheels. F. O. B., of 'Vis.If you could refer to any engraviugs which have appeared in our columns for the last six years which are as poorly executed as yours, you might have reason to complain at our rejecting your cuts ; but we' wish you, and all others who desire us to illustrate their inventions in our columns, to understand that we keep designers and engravers for the express purpose of getting up the engravings for our paper, and so long as we charge no more than other engravers for doing the work, we prefer to have it done under onr supervision. No one has cause to demur at what you term " fastidiousness." H. R., of N. Y.A cable like tho Atlantic one would ntver float in any depth of water. The idea is a very popular fallacy. M. A. J., of Pa.We do not know of any book in which you will find thcinformation you wish, but we can tell you that transparent colors are usually made of what are called silica colors ground with a transparent varnish in the ordinary way. J. P., of Wis.Your invention is almost similar to one which we have described in a previous number of the ScientifiO American, and in our opinion is not patentable, there being no novelty in floating buoys attached to ships. C. A. n., of Mich.It is impossible to execute me chanicalengravingscorrectlyf rom n daguerreotype. A model is preferable to drawings to get up engravings from. It enables us, in describing the invention, to better understand the advantages and operation of the machine. David Sexton, of Wytheville, Va., wishes to purchase one of Norton & Owen's double-cylindered bark mills. rr. "VV. Il, of Ohio.Your communication has been received, and we are SalTY to say it is too abstract for the generality of our readers. M. A., of Ind.The simplest way to increase your draft would be to add a felY feet to the hight of the chimney. We cannot tell you whether a saving of fuel would be effected by such increase. Too strong a draft is not economical, as it causes too much heat to escape up the chimney, and too weak a one, by not effecting perfect combustiollresults, also in loss. D. A. B., of Ala."Te think a gun constructed as you propose would be very liable to burst unless you used an exceedingly short barrel. A sudden or percnssive force is not the most effective in throwing projectiles. It is by reason of its very sndden combustion that gun cotton is not 80 effective as gunpowder in throwing a ball, while it is much more likeJy to burst the gun. We cannot sec that you would gain any advantage over Barker's mill by your spiral tube. The reaction would be in proportion to the fall only. E. W. P., of Mass.Your communication on the manufacture of oil of vitriol very correctly details the method practised twenty years ago ; but our article is a description of the method pursued to-day, and was written by an analytical chemist who b practically acquainted with the present method. J. R., of N. O. Your remittance to pay for repairs on model was duly received. W. A. McC, of Pa.The best method of freeing coal from sulphur in the coking process is to coke in close ovenH, and if the whole of the sulphur is not then freeu, have a small hole and sliding shutter in the door to ad mit a small quantity of air and occasionnlly let some in. Coke slow, and we think you will get rid of it. Send us a description of your process, and also that of making crude oil, and we will further advise you. L. S., of N. O.There have been a great many patents issued for machines capable of sawing two sides f tapering slabs for monuments. * T. C., of N. Y.Your idea of the gyroscope Is truer J than many we have seen, but We have given up calling S the attention of our readers to it, as its novelty is gone. ? E. F., of Ct.There is no truly valuable work on pnmps, vulvcs, hydrostatic presses, &c. Ewbank's Hy. dranlics is a good general history on the subject of hydraulics, and such subjects as are collateral to it. 'V. F. M., of Md.'Ve think you can procure Professor Mahan's works from Wiley & Halstead, of this city. You can pursne a course of study on civil engineering at tho Polytechnic College, Philadelphia, J. J., of N. Y.The putty used by gilders is composed of whiting and size. Yon must find the proportions to suit yourself, as each frame maker uses it differently. F. W., of Mass.It is a burning shame that the Commissioner of Patents should have the disposal of so small a portion of the Patent Office Reports which are printed. The Patent Office should have the distribution of three-fourths of the number issued, for it has a complete register of the names of all parties entitled to them; but, under the present system of distrIbution, the mem bers of Congress have a large proportion of the Patent HeportR, and, of course, they distribute them among a class of their constituents who have the most influence at the polls. The mechanic and the inventor are not usually of that class. 'Ve would recommend you and others to ask the member of Congress from your respective district to send you the Commissioner of Patent's Report, and if those members are fit representatives of their districts, they will not refuse to respond to the request. The Commissioner hus more orders for them than he can fill. W. C. J., of Kenwood.Smith Beers, of Nangatuck, Ct., has a patent for an odometer which we believe to be a good oue. H. H., of Pa.The best wood is mahogany, next to that, soft pine. Shellac varnish will answer your purpose. To apply emery to a rifle, you had better use a weak solution of glne, and dust the emery on. Money reCeived at the Scientific American Oflice on account of Patent Office bUSiness, for t.he week ending Saturday, November 7,1857 : M. T., of N. Y., $30 ; J. II., of Ind., $30 ; J. D. S., of Vt.,$25; R. L.,of Wis., $30; II. A. S., of Vt., $30; J. L., of Mass., $10 ; G. & S., of Vt., $30 ; J. M. S., of Conn., $30; A. A. N., of Ill., $22 ; E. A. C., of Conn., $55; J. H. H., of Pa., $30 ; 'V. YcK., of Cal., $45 ; T. V., of Cal., $10; G. II. 'Y., of Wis., $G95; E. g., of Ill., $30; L. &M.,of Mass., $25; C. 'Y., of Pa., $10; J. V. J., of Mich., $10 ; W. B., of N. Y., $575 ; W.:A. Y., of N. C., $55; N. R. A., of N. Y., $30; II. H.,ofN.Y., $30; W. C. W., of N. Y., $110; J. C. S., of Mass., $155. Specifications and drawings belonging to parties with the following initials have been forwarded to the Patcnt Office during the week ending Suturday, November 7, 1857 : J. D. S., of Vt.; J. H., of Ind. ; A. A. N., of Ill. ; L. K., of Ohio ; L. & M., of Mass.; E. A. C., of Conn. ; W. C. W., of N. Y., (2 cases); J. C. S.,of Mass., (3 cases). Literary Notices IrxtJSTBATED Annual Register of Rueal Affairs foe 1855-G-7.Luther Tucker & Son, Albany. This i8 a re-issue of a work cnJled the " Annual Hegister," and it pleasantly treats of all thing8 connected with rural lifehouses, gardens, animals, fruits aud flowers aro all hm'ewell and ably described, and they are illustrated with 440 engravings. Most of the new and useful implements used in cultivation or gathering the fruits ot the earth find a place,and it iH a nice and valuable book for the farmer or any one living in thecountry. Hunt's Merchant MagazineFreeman Hunt, New York. The November number is full of useful intelligence and matters of iuterest to the commercial man, while one of its most valuable features is its nautical intelligence, which is an item not found in any other periodical. TO OUR SUBSCRIBERS. Give Intelligible Directions.We often receive letters with money encloscd, requesting the paper sent for the amount of the enclosure, but no name of State given, and often with the name of the Post Office also omitted. Persons should be careful to write their names plainly when they address publishers, and to name the Post Office at which they wish to receive their paper, and the State in which the Post Office is located. Receipts.When money is paid at the office for subscription, & receipt for it will always be given; but when subscribers remit their money by mail, they may consider the arrival of the first paper a bonafide acknowledgment of the receipt of their funds. The Post Office law does not allow publishers to enclose receipts in the paper. SCliSCEIBEEH TO THE SOIENTIFIC AMERICAN who fail to receive their papers regularly, will oblige the pub_ lishers by stating their complaints in writing. Those who may have misecd certain numbers can usually have them supplied by addressing a note to the office of publication. EveRy SubscribeR would do well to try and get one or more of his neighbors to send their names with his own, even if he has no wish to avail himself of our club rates. The larger the package of papers sent to one addresa, or the same Post Officu, the greater is the certainty of getting the paperregularly. Asingle paper is sometimes mislaid or overlooked in sorting the mails nt some one of the intermediate post offices through which,It has to pass ; while, on the contrary, we have noticed that a large package seld om fails t reach its proper destination.
This article was originally published with the title "Correspondents"