Objection may be made to the arrangement of the battery on the score of waste of zinc by local action, because of the electro positive metal being exposed to the chromic liquid; but if the battery be out of action and the circulation stopped, the zinc amalgam is protected by the immobility of the liquid and the formation of a dense layer of sulphate of zinc on its surface. When in action, that effect is neutralized from the fact that carbon in chromic acid is more highly electro-negative than the chromate of mercury formed upon the zinc amalgam, and which appears to be the cause of the dissolution of the zinc even when amalgamated in the presence of chromic acid. The solution may be repeatedly passed through the battery until the absence of the characteristic warmth of color of chromic acid indicates its complete exhaustion. During a description before the Society of thermo-electric batteries some time ago, Mr. Preece mentioned that five of the thermopiles which were being tried at the Post-Office were doing the work of 2,535 of the battery cells previously employed. Thirty of the cascade cells would have about the same potential as five such thermopiles, but would supply three and a half times the current, and be capable of doing the work of 8,872 cells if employed upon the universal battery system in the same manner as the thermo batteries referred to. Although this battery will do all that is required for a Thomson recorder or a similar instrument much more cheaply in this country than the tray battery, and with half the number of cells, I do not think it would be the case in distant countries, on account of the difficulty and cost of transport. A solid compound of chromic and sulphuric acids could be manufactured which would overcome this difficulty, if permanent magnetic fields for submarine telegraphic instruments continue to be produced by electric vortices. In conclusion, and to enable comparisons to be made, I may mention that the work this battery is capable of performing is 732,482 foot pounds, at a total cost of 1s. 6d. * * * * * [FROM THE SCHOOL JOURNAL.] PERFECTLY LOVELY PHILOSOPHY. CHARACTERS: Laura and Isabel, dressed very stylishly, both with hats on. Enter hand in hand. _Laura_. My dear Isabel, I was so afraid you would not come. I waited at that horrid station a full half hour for you. I went there early on purpose, so as to be sure not to miss you. _Isabel_. Oh, you sweet girl! _L_. Now, sit right down; you must be tired. Just lay your hat there on the table, and we'll begin to visit right off. (_Both lay their hats on the table and stand near by_.) _I_. And how have you been all the ages since we were together at Boston? _L_. Oh, well, dear; those were sweet old school days, weren't they. How are you enjoying yourself now? You wrote that you were taking lessons in philosophy. Tell me how you like it. Is it real sweet?