MECHANICS AND USEFUL ARTS. 109 



covers. The roller is equal in length to the covers, and has a longitudinal 

 groove cut in it its entire length ; it also has grooves cut in it circumferentially 

 at equal distances apart. Metallic rings are fitted loosely into the grooves. 

 The music sheets, maps, engravings, or other articles, are secured to the rings 

 within the portfolio, by means of a needle and thread. 



Improvement in Melodeon-s. In ordinary -melodeons the keys are quite 

 short ; they do not extend back like piano keys, but terminate just at the 

 fulcrum. Attached to the under side of each key, in a melodeon, is a wire 

 projecting downwards, known as a "push-down pin;" when a key is pressed, 

 this phi comes hi contact with a pah* of corresponding reed valves, opens the 

 same, and musical sounds result. In the best melodeons each push-down pin 

 opens two valves, so that for each pressure of a key, two different sounds 

 are produced. An invention, by T. F. Thornton of Buffalo, N. Y., consists 

 hi elongating the rear end of the key, and placing upon the upper surface 

 of the extended part a " push-up pin," arranged in connection with an 

 additional set of reeds and valves. The result is that whenever a key is 

 touched, four musical sounds, forming a chord, are produced, instead of two, 

 as heretofore. 



SEROPYAN'S PROTECTIVE PROCESS AGAINST COUNTERFEITING. 



In the plan proposed by Mr. Seropyan, the paper, before the printing, is 

 tinted over the whole surface by means of an oil color, excepting that in 

 certain parts of each bill, five or more, the denomination is indicated in large 

 letters or figures, which are left white like the uncolored paper. After this 

 comes the printing of the engraved plate. To alter such a bill, it is necessary 

 to color up, precisely to the general tint, the white letters and figures, 

 expressing the denomination, so as completely to obliterate them, and, at the 

 same tune, not obscure the engraving over them. 



The new plan prevents photographic copying by means of the peculiar 

 color and nature of the ink, and also of the color of the paper ; and from the 

 results of trials with Seropyan's bills which have been examined, as well as 

 from known principles with regard to the impossibility of obtaining distinct- 

 ness hi a photograph when the object copied has certain shades of color, it is 

 believed that the method is a complete protection. 



In copying a print by any anastatic process, the ink of the letters, or of the 

 engraved lines, does not absorb the corrosive liquid with which the paper is 

 moistened, and upon this difference between the clean paper and the ink 

 lines, the possibility of anastatic copying depends. Now hi the Seropyan 

 mode of printing bills, the general face of the bill being covered with oil 

 color, there is no such distinction as is here required ; whatever means may 

 be used to remove the oil will obliterate the printing. Hence the anastatic 

 method cannot possibly be used in copying such bills. 



POWERS' SYSTEM OF MODELLING. 



The following is a description of the new method of modelling recently 

 introduced by Powers, the American sculptor : The original block is con- 

 structed hi a masonry of small bricks of " gesso." laid in plaster, and of 



