64 ANNUAL OF SCIENTIFIC DISCOVERY. 



NEW GASOMETER. 



THE Boston Gas-Light Company have just erected an immense 

 new gasometer. It is 80 feet in diameter, 40 feet high, and the 

 crown of the roof is 5 feet, making the entire height 45 feet; its 

 working capacity is 200,000 cubic feet. It weighs 116,000lbs. 



IMPROVED BANK-NOTE PAPER, FOR THE PREVENTION OF 



FRAUD. 



A COMMISSION, appointed by the French Academy of Sciences, in 

 connection with the French government, whose object it was to dis- 

 cover a paper to be used for bank-notes, deeds, &c., which should 

 resist the arts of forgers and counterfeiters, have reported to the 

 Academy that their etforts have at length been crowned with success. 

 They take a glance at the repeated endeavors which have been made 

 to effect this desirable object, from which it appears that the experi- 

 ments and investigations have been almost constantly going on since 

 1826, during which period numerous plans have been submitted, to all 

 of which there has hitherto been some objection. The successful 

 competitor, M. Grimpe, has from the beginning sought to attain 

 the desired end by means of a delible device extending all over the 

 surface of the paper, and composed of lines too delicate to be repro- 

 duced by hand, and which, being printed with delible ink, should be 

 exposed to attack by all the agents which affect writing, and when 

 once effaced, could not be restorable by the most skilful hand, or by 

 any printing process. The principle, as improved and adopted, con- 

 sists in covering the paper with a microscopic device, printed on both 

 sides with delible ink by means of a cylinder. The nature of the 

 device, the mode of engraving the cylinder, and the nature of the ink 

 and paper, have, during the last eleven years, been the object of inces- 

 sant discussion and study on the part of some members of the com- 

 mission. It has finally been concluded to engrave the device upon 

 the cylinder by means of a steel roller, having the device upon it in 

 relief, which, by strong pressure, reproduces it in intaglio upon the 

 copper cylinder. After experimenting with various devices, such as 

 concentric circles, hexagons, &c., microscopic stars have finally been 

 decided upon. This device presents insurmountable obstacles to its 

 reproduction by hand. The stars are produced by a single steel 

 punch, or die, having a single star engraved upon it; which punch, 

 being highly tempered, is caused to stamp the stars all over a soft 

 steel cylinder, which is then tempered, and can be used to reproduce 

 the device, as often as required, upon other cylinders, especially cop- 

 per ones. The cylinders to be printed from are now engraved in re- 

 lief, instead of intaglio, as by the former method the ordinary writing- 

 ink can be used, which is not the case when printing from intaglio. 

 The commission also insist upon using paper made by hand, a sheet 

 at a time, and sized by gelatine, which is always rather uneven on 

 account of the water-lines and there being no division of the pulp. 

 This sort of paper is much more durable than any made by ma- 

 chinery. 



