The sixth lecture is devoted to the further illustration of the action of crystals upon light; uniaxal and biaxal crystals, circular polarization, and the chromatic effects produced by rock-crystals; the conferring of double refractory power by sonorous vibrations; and the magnetization of light. Although the syllabus is short, it covers a good deal.
We have sketched the course of six lectures. The materials touched upon are ample to fill the six to overflowing, allowing an hour and a half for each lecture. A seventh very striking lecture might be given, he says, on the identity of light and heat—every experiment made in the optical lecture being shown capable of repetition with pure lightless radiant heat, the thermo-electric pile and galvanometer being substituted for the eye. He has made an arrangement for the projection of the galvometer-dial upon a screen, which renders it visible to any number of people.
As he worked at the subject, the desire grew upon him to do it more and more thoroughly, and to spare no expense as regards apparatus. He has accordingly purchased between three and four hundred pounds sterling worth of new instruments; and has gone over all the experiments, so as to render every thing sure, and in a manner worthy of the subject and of the occasion.—United States Railroad and Mining Register.
|THE COCOA-NUT PALM, AND ITS USES.|
COASTING along Ceylon and the Malabar littoral, the voyager will notice the tall palm-trees, which appear as if growing in the sea, and will learn, on inquiry, that they are of the variety Cocos nucifera, or the loving cocoa-nut tree.
Though the sight of these never-ending groves may at length pall upon the eye of the traveller, yet he will do wisely if at eventide, while the ship is becalmed, he should take the "jolly" boat and land on the silent beach. In a few minutes he will stand in a "grove of palms," and must be of a somewhat stolid temperament if he does not feel something like a new sensation, as he looks aloft and listens to the rustle of the first breath of the sea-breeze, as it gently waves the graceful fronds or leaves overhead. Those who have been in the East will, as they read these lines, recall the sound, and with it, perhaps, may be brought to mind many pleasant days and the faces of old friends who sleep beneath the southern cross. Those who have not strolled under the welcome shade afforded by the fern-like canopy, will remember Thomson's lines: