Proceedikos of tbe Polytechkic Association. 723 



the winter, and repeat in the succeeding season the process detailed 

 above. Thus it will be seen at once, the curculio differs from the 

 apple-worm or codling moth, which is also double-brooded, in this 

 that the former passes the winter in the perfect state and the latter in 

 the larva and pupa states. The practical inference to be drawn from 

 this discovery is that b}'- destroying in June or early in July the first 

 wormy fruit that produces the first brood, the crop of curculios for 

 the current year is diminished. No reliable method for driving off 

 the curculios has yd been discovered. It is proper to here state that 

 Dr. Trimble, entomologist of the State of New Jersey, has made 

 experiments in relation to the production of distinct broods. He has 

 taken the earliest curculio of the season and watched their movements. 

 He has never been able to discover embryo eggs in the females until 

 the next spring, and never has he seen the sexes approach each other 

 during the first season of their maturity. Like many otlier insects 

 curculios do not increase their number until the second year. They 

 hybernate during the intervening winter. Further experiments should 

 be made to finally settle this question. 



A Constant Single Liquid Battery. 

 More than 20,000 elements of Leclanche's peroxyd of manganese 

 battery are now in use on telegraphs connected with the French and 

 other European railways. Twenty-eight of these elements have been 

 found equal in practice to a series of forty elements in a Daniel 

 battery. As peroxyd of manganese has considerable conductability, 

 resembling in this respect the metals, Leclanche was led to use it as 

 the positive element in connection with zinc as the negative. After 

 various tests of solutions of different salts he decided to employ, as 

 the liquid, a concentrated solution of salt of ammonia, the sal ammo- 

 niac of commerce being preferred. He uses the black and brilliant 

 peroxyd of manganese in the form of large grains, mixed with an 

 equal quantity of powdered carbon in a porous jar. The electricity 

 obtained is collected and used by means of a carbon plate. Li pre- 

 paring this battery, care should be taken that the solution does not 

 rise more than half way up the porous vase, as the drier its contents 

 are the better is the condition for working. 



AiE Tight Galvanic Battery. 



C. T. and J. N. Chester have constructed a very compact and pow- 

 erful battery for medical uses which has the merit of being always 



