234 Triangula t ion.'— Experiment by M. Dcebereiner. 



tained that his principle of protecting the copper sheathing of 

 ships by the contact of l-200dth of iron, is perfectly success- 

 ful, even in the most rapid sailing and in the roughest sea ; 

 and Dr. Tiarks, by direction of the Board of Longitude, has 

 connected, by chronometrical observations, the trigonometri- 

 cal surveys of Denmark and Hanover with that of England ; 

 so that the triangulation of a great part of Europe may be now 

 said to form one system, M. Arago and Captain Kater having 

 two years ago connected the surveys of England and France 

 by observations between Calais and Dover. In the course of 

 this last expedition to the North Seas, the longitude of the 

 Naze of Norway, a point of great importance in navigation, 

 has been accurately ascertained, and some other useful data 

 for correcting the nautical maps of Europe gained. 



CONVERSION OF THE OXALATE AND FORMIATE OF AMMONIA 

 INTO HYDROCYANIC ACID : BY M. DCEBEREINER. 



Professor Dcebereiner has proved by experiment the ex- 

 istence of a phaenomenon whose possibility he had inferred 

 from calculation. This phaenomenon is the conversion of the 

 oxalate of ammonia (NH^ + PO*) into cyanogene and water 

 (CN + J HO). If this salt is mixt with oxalate of manganese, 

 and heated with a spirit lamp in a glass tube closed at one 

 end, we obtain, besides carbonic oxide and carbonate of ammo- 

 nia, water and cyanogene ; but the cyanogene is speedily con- 

 verted, by the action of the carbonate of ammonia and the 

 water, into hydro-cyanic acid. 



The formiate of ammonia (NH 3 -fC0 3 H) decomposed in a 

 glass retort is also converted into hydro-cyanic acid and water 

 (CNH + J HO).— (Repert.fiir die Pharm. vol. xv. p. 424.) 



ON THE TOTAL ABSENCE OF WASPS THIS SEASON. 



To the Editors of the Philosophical Magazine and Journal. 



Gentlemen, — Among the many curious and at present un- 

 explained circumstances in the natural history of insects, we 

 may consider the total absence of particular tribes in certain 

 seasons, while in others they appear at their wonted time in 

 vast and unusual numbers. Wasps in this district have of late 

 afforded a striking example of this irregularity. For many 

 years past these troublesome insects have been very numerous 

 in the early part of the autumn. They usually appear in Au- 

 gust, become very plentiful in September, and disappear by 

 degrees in October. Towards the close of the summer 1821, 

 they were so numerous as to become quite a pest ; during 

 September every window was full of them, and several thou- 

 sands 



