Cheap Postage.—The postage on the Scientific American, to subscribers residing within the State of New York, will be but 13 cts. per annum henceforth, instead of 13 cents per quaxter as formerly, and will be delivered at the most remote parts of the United States for 26 cts. per annum, whereas the postage formerly demanded at distant offices was $1,20 per annum. The saving produced by the reduction of newspaper postage under the new statute, is no inconsiderable item, and many who could not afford to subscribe for the Scientific American, under the old law, can now withstand the expense. Baok Numbers and VoLUMES-In reply to many interrogatories as to what back numbers and volumes of the Scientific American can be furnished, we make the following statement :—Of Volumes I,2 and 8-none. Of Volume 4, about 20 Nos., price 60 cts. Of Volume 6, all but four numbers, price, in sheets, $1. Of Volume 6, all; price in sheets, $2; bound,$2,76. Of Vol. 7, all; price in sheets, $2; bound, $2,76. ADVERTISEMENTS. Terms of Advertising. 4 lines, for each insertion, - - 5Octs. 8 “ “ “ - - $1,00 12 “ “"- - $1,50 16 “ “ “ _ - $2,00 Advertisements exceeding 16 lines cannot be admitted ; neither can engravings be inserted in the advertising columns at any price. All advertisements must be paid for before inserting. Patent Claims—Persons desiring the claims of any invention which has been patented within fourteen years, can obtain a copy by addressing a letter to this office—stating the name of the pa tentee, and enclosing one dollar as fee for copying Patent Laws, and Guide to Inventors.—We publish, and have for sale, the Patent Laws ofthe United States. The pamphlet contains not only the laws but all information touching the rules and regulation of the Patent Office. Price 121-2 cts. per copy. Foreign Subscribers—Our Canada and Nova Sco- tis.patrons are solicited to compete with our oiti- zens for the valuable prizes offered on the present Volume. [It is important that all who reside out of the States should remember to send fifty cents additional to the published rates tor each yeaxly subscriber; that amount we are obliged to pre-pay on postage.] Infallible Rule—It is an established rule of this office to stop sending the paper when the time for which it was pre-paid has expired, and the publishers will not deviate from that standing rule in any instance. Receipts—When money is paid at the office for subscriptions, a receipt for it will always be given, but when subscribers remit their money by mail, they may consider the arrival of the first I'aper a bona- fide acknowledgment of the receipt of the funds. Give Intelligible Directions—We often receive letters with money enclosed, 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. To CORRESPONDENTS—Cdndense your ideas into as brief space as possible, and write them out legibly, always remembering to add your name to thecom- munication. Anonymous letters receive do attention at this office. If you have questions to ask, do it in as few words as possible, and if you have some invention to describe, come right to the business at the commencement of your letter, and not fill up the best part of your sheet in making apologies for having the presumption to address us. We are always willing to impart information if we have the kind solicited. Patentees—Remember we are alwayswilling to execute and publish engravings of your inventions, provided they are on interesting subjects, and have never appeared in any other publication. No engravings are inserted in our columns that have appeared in any other journal in thu t*yT -««J wemust bepermitted to have the engraving executed to suit our own columns in size and style. Barely the expense of the engraving is charged by us, and the wood-cuts may be claimed by the inventor, and subsequently used to advantage in other journals. 5 0-HORSE STEAM-ENGINE FOR SALE.--A new and superior Engine and Boilers, with all connections, &c., complete, and ready to be put in operation without further additions. The above, with plain exterior finish, is made of the best of materials and with the utmost attention to perfection of construction, arrangement and workmanship. For further particulars, apply to J. CUMMING Columbia Foundry, Duane-street, New York. 1" SECOND HAND MACHINES FOR SALE Cheap. A double-rigged Scroll Saw, 1 power Mortice Machine, 1 circular Saw, mandrell, bench,&c., 1 upright Saw for slitting panel stuff, 1 Lathe, Tools, &c.; 1 Boring Machine for Blinds: all in perfect running order. For further particulars, apply in person or by mail (post paid) to HENRY E. ACKENS'SSteam Sash Blind and Door Factory, Sing Sing, N. Y. I12t* TO FOUNDRY MEN AND MACHINISTS.—Metallic Letters and Figures to put on Patterns.- Roman Style-Size, 5-16, 3-8, 7-16, and 1-2, price3c. each; 9 16, 5-8, and 3-4,4 cts.; 1 in., 6 cts.; 11-4 7 cts.; 112 8 cts.; 2 in. 10 cts. N.B—The above are the sizes on the face of the Letters. Also, Gothic Style—Size, 1-4 and 1-2, Price 3 cts. each:- (Roman Style) Branding Irons—1-4, 3 8 and 1-2 in. 4 cts. each; 5-8, 5 cts., and 3-4 in. 6 cts. Manufactured by COWING&CO., Seneca Falls, N. Y. Orders solicited. They can be sent to ail parts ofthe Union, either by Mail or Express. We weigh all Packages and send them the cheapest way.11 2* COTTON MACHINERY FOR SALE-Four Filling Frames, of 144 spindles each, made in the best manner and nearly new ; price $1 per spindle; other machinery for sale equally low. Apply to E. WHITNEY, New Haven, Conn.11 6" IRON FOUNDERS MATERIALS—viz.: Ame- ricanhard white and grey Pig Iron; No. 1 Scotch Pig Iron, Iron and Brass Moulding Sand ; Fire Sand and Fire Clay ; Core Band and Flour. E nglish and Scotch patent Fire Bricks—plain, arch, and circular, for cupolas. Pulverized Soapstone and Black Lead. Sea Coal, Anthracite and Charcoal Foundry Fa cings of approved quality, always on hand and for sale by G. 0 ROBERTSON, office 135 Water street, (corner of Pine) ,N. Y.11 6*