2 H THE POPULAR SCIENCE MONTHLY. 



The sixth lecture is devoted to the further illustration of the action 

 of crystals upon light ; uniaxal and biaxal crystals, circular polariza- 

 tion, and the chromatic effects produced by rock-crystals ; the confer- 

 ring of double refractory power by sonorous vibrations ; and the mag- 

 netization 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 be- 

 ing substituted for the eye. He has made an arrangement for the pro- 

 jection 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 appa- 

 ratus. He has accordingly purchased between three and four hundred 

 pounds sterling worth of new instruments ; and has gone oyer 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 Min- 

 ing Register. 







' THE COCOA-NUT PALM, AND ITS USES. 



By C. E. LOW. 



C" CASTING 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 grace- 

 ful 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 : 



