PROCEEDINGS OF THE POLYTECHNIC ASSOCIATION. 851 



Sfraduated. Mr. Lea thinks the whole instrument would have 

 great precision in working, were it made of metal instead of wood. 

 We hope some American mechanician Avill remedy the evils com- 

 plained of, and provide photographers with an absolutely correct 

 camera. 



The Camel in Australia. 

 The camel has been introduced into Australia, and has proved 

 well adapted to the dry regions of that country. In a recent expe- 

 dition, seventy horses, fourteen camels, and fifteen men were em- 

 ployed. The springs upon which the}'- depended for water hav- 

 ing dried up, the horses fled; the men resorted to their stores of 

 spirituous liquors, while the camels traveled on without drink. 

 The §aravan was thus enabled to continue its journey until they 

 reached Thompson river. 



Dangerous Toys. 

 In Europe the rage for Pharaoh's serpents, a scientific toy con- 

 sisting of the sulpho-cyauide of mercury, had hardly been cheeked 

 by showing that it could not be burned without the disengagement 

 of dangerous fumes, when another mischief-making plaything 

 appeared under the name of "Devil's tears." They consist of a 

 little oval capsule covered with cotton and a thick layer of varnish; 

 inside the capsule is a little pill of coarse paste made up appa- 

 rently of the metal potassium. At a little distance they resemble 

 red sweetmeats or red berries, and might easily be mistaken by a 

 child, not old enough to read the directions, and swallowed, which 

 would produce instant death. "Juno's tears" and "Witches 

 tears " are imitations containins; the metal sodium. Either of 

 these metals have such a strong aflinity for oxygen that they will 

 abstract it from water. The capsule dances about on the surface 

 of water while burning, and often throws among the wondering 

 spectators red hot globules of the hydrate of potassium. 



Artificial Limbs. 

 We gave in the last volume of the Transactions of the American 

 Institute, very full descriptions of nearly all the best artificial 

 limbs invented and made in this country. Under the act of Con- 

 gress providing limbs for soldiers, passed July 16, 1862, there 

 have been supplied up to July 1, 1866, 3,981 legs, 2,240 arms, 55 

 hands, nine feet, 125 surgical apparatus, and it is supposed about 

 one thousand limbs are yet to be furnished. 



