Barns often struck by lightning, 345 



my object for introducing this topic now is, more particularly 

 to state, that the phosphorus was ignited, on one occasion, 

 at the distance of twenty-fvvo feet, notwithstanding the inter- 

 position of a large pane of glass, twenty inches square. This 

 shows, that glass is permeable by radiant heat from very 

 hot bodies. I had my hand on a lever, to which the pane 

 was attached in order to raise it ; but I had not time to get 

 it under way. For this experiment, the phosphorus was 

 melted on cotton, at the bottom of a tube, and the cotton 

 afterwards divided, under water, into pieces of a proper size. 

 Being placed in a candle wick, the candle may be lighted 

 by the mirrors, which is a very pretty result. 



4. Construction of Galvanic ApparaiusJ^ 



(See Professor Hare's Memoir in the present volume.) 



I am constructing a galvanic apparatus, in a glass jar, two 

 and a half inches in diameter, by eight inches in height, of 

 coils of copper and zinc ; the zinc plates are about nine 

 inches by six, and are rolled up with the copper hy means 

 of a mandrel, and two pieces of soal leather interposed, one 

 eighth of an inch thick, the copper beginning on the inside 

 and ending on the outside ; so that it takes fourteen inches 

 of this metal. There will be eighty pairs only, at first. The 

 soal leather is used merely to give them the proper spiral; 

 and is, of course, withdrawn, when they are taken off the 

 mandrel. Narrow pieces of wood are employed to keep 

 them apart afterwards. 



* Although the description of this apparatus has been published, we have 

 thought it best to preserve this memorandum, because it contains some usefu? 

 directions relative to the mechanical construction. — Ed. 



Art. XV. — Peculiar liahility of Barns to he struck hj 

 lightning. — Editor. 



The fact, that barns are much more frequently struck by 

 lightning than any other description of buildings, is notori- 

 ous. Every summer presents a calamitous list of these 

 buildings burnt in thunder storms; and it is no very uncom- 

 mon occurrence, that several are consumed by the same 

 thunder storm. Instances are at hand in sufficient numbers; 

 but, as these occurrences are so frequent, it is not thought 



Vol. III.....N0. 2. 44 



