148 RoyaUcademy of Copenliagen. — Suc'iety of Haerlem. 



press be not at hand, the impression may be taken off Itv treading 

 them all over with the bare foot, taking oaie to interpose a few 

 sheets of p iper between the foot and the siieet that is to receive 

 the impression : if oil paint cannot be had, the smoke of a candle 

 will answer. Another method of procuring a copy, is by taking 

 a cast from the plate in plaster of Paris : in this case the reading 

 will be more easily discerned if the incisions have some dark- 

 coloured paint rubbed into them before the cast is made ; or, if 

 paint cannot be procured, by first smoking the plate all over, 

 and then wiping the surface clean, which will leave the lamp- 

 black in the incisions. A fourth method, and which gives a very 

 good impression, is by laying over the plate several folds of soft 

 white paper, previously soaked for some hours in water, and then 

 with care forcing the paper, by mere pressure with the fin^^ers, 

 to enter to the very bottom of the incisions: if it is apprehended 

 that the paper has not entered deep enough (which however may 

 be easily known by gently lifting up one of the corners of the 

 paper for inspection), it may be more efiectually forced in by 

 laying two or three folds of linen over the paper j and then, 

 gently and patiently, beating it all over with a light wooden 

 mallet: in this way a very accurate impression may be taken in 

 papier mache ; the paper should be left for some time in contact 

 with the plate, but not till tjuite drv, as shrinkage takes place 

 during the drying, wliich might hurt the sharpness of the im- 

 pression if then fdund entangled in the engraved incisions. 

 AH these impressions will be reversed, but may be read forward 

 with the help of a mirror.] 



In the museum of this Society there are, among other curio- 

 sities, a piece of rattan from Nepaul, 84 feet long, a snake 

 with two heads, specimens of Mosaic from Agra and Golconda, 

 crystal images from Nepaul, and sculptures from Persepolis, 

 Java, &c. 



ROYAL ACADEMY, COPIiNHAGEN. 



This Academy has proposed the following as a prize question 

 respecting the variation of the compass : " Num inclinatio et 

 vis acus magneticas iisdem, quibus declinatio, diurnis variationi- 

 bus sunt su'njectae ? Num etiam longiores, ut declinatio, habent 

 circuitus ? Num oenique has variationes certis finibus circum- 

 scribere possumus ?" — Prize, 50 Danish ducats. 



SOCIETY OF SCIENCES, HAERLEM. 



This Society has proposed the ibilowing prize question : " What 

 advantage has medicine derived from the reformation and ex- 

 tension of chemistry since the time of Lavoisier, in making us 

 better acquainted with the chemical agency of the medicines 



usually 



J 



