C. A. Joy on the Chimenti Pictures, 199 
causing them to part in the magnetic directions north and south. 
The presence of iron in the coal might have facilitated this 
are no such planes, nor jointed structure of any kind, in the bi- 
ina of coal, not thicker than paper, shows these planes perfectly, 
while nothing of the kind is found in the bituminous slate above 
and below. There is no jointed structure to be found in any of 
our rocks associated with the coal. So far as I have observed, 
these joints are generally found in rocks which have been sub- 
jected to heat as well as pressure. If this is so, we should not 
expect such joints in the coal; as in the West, it has never been 
subjected to any heat, the coal still retaining its full and normal 
quantity of bitumen. 
ther lessons may be learned from this seam of coal, but I 
defer their consideration to another time 
ArT. XX.—On the Chimenti Pictures ; by Cuaruzs A. Joy, 
Professor of Chemistry in Columbia College, New York. 
Pyorograpus of the famous Chimenti drawings have been 
exhibited in this country, upon the back of which was pasted 
the following announcement: oe 
‘The stereoscopic pictures executed by Jacopo Chimenti, born 
640. These remarkable pictures, from the Museum 
Wicar at Lille, were found to be stereoscopic by Dr. Alexander 
Tum Brown, when visiting that city in 1859 with his brother, 
Dr.John Brown. Sir David Brewster communicated this curious 
discovery to the Photographic Society of Scotland, and Dr. 
Brown’s account of it was published in the Photographic J: ournal 
of May 15, 1860, and in the Encyclopedia Brittanica, article 
Stereoscope. “a 
In these works, Sir David Brewster expressed the opinion, 
that as Baptista Porta had, in 1598, published (after Galen, born 
A.D, 130,) the true principle of the stereoscope,” Chimenti had 
~ In order to satisfy himself of their stereoscopic character, Sir 
Vavid applied for a photograph of them, but failed in procuring 
it. Mr. \ eclared 
* See his Treatise on the Stereoscope, pp. 6 and 8. 
