PATENTEES—Remember we are always willing to ex ecute and publish engravings of your iaventions, provided they are on interesting subjects, and have never appeared in any other publication. No engravings are inserted in ourcolumnsthat have appeared in any other journal in this country, and we must be permitted to have the engraving executed to suit out* own columns in size and style. Barely the expense of the engraviDg is charged by UB, and the wood-cuts may ba claimed by the inventor, and subsequently used to advantage in other journals. GIVE INTELLICHBLE DIRECTIONS—We often receive letters with monoy 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 thei wish to receive their paper, and the State in which the post office i3 located. BACK NUMBERS AHD VOLUMES—In reply to many interrogatories as to what back numbers and volumes of theScientifio American can be furnished, we make the following statement-—Of Volume* 1, 2 3 and 4—none. Of Vol. 6, all but sis numbers price, in sheets, $1; bound, $[75. Of Volume 8 all; price in sheets, $2; bound,$2,75. Of Vol. 1 all; price in sheets. $2; bound, $2.75. Of Vol. 8, all the back numbers subseauent to No. J7, but PATENT CLAIMS—Persons desixmg the claims Of any invention which has been patented within fourteen years, can obtain a, copy by addressing a letter to this office—atating the name of the pa ten tee, and enclosingonedollaras fee for copying. PATENT LAWS, AND GUIDE TO INVENTORS.—We publish, and have for sale, the Patent Laws of the United States. The pamphlet contains not onlj the laws Dut all information touching the rules and regulation of the Patent Office. Price 121-2 ct Der cnpv A D V ERTISEMENTS/J" Term* of Advertising. 4 Hoea, for eaofl insertion, - - 60cts 8 tl '- ' - $1,00 12 " ki u - $l,60 16 " :i *! - $2,00 Advertisements *-tceeding 16 lines cannot be admitted; neither can engravings be inserted in the advertising columns at any price. JJ=- All advertisements must be paid for before inserting.