8 
Dr Colladon’s Narrative of a Descent 
Dr Wollaston had discovered that the Iceland Mesotype differ- 
ed from the mesotype of Auvergne, in the measure of its angles 
as well as in its chemical composition. Mr Brooke detected a 
new mineral species in the mesotype of Dunbartonshire ; and I 
have found other two new minerals in the Nadelstein of Faroe 
and the Mesotype of Greenland. The optical structure of these 
Jive different species of mesotype I have examined with much 
attention, and have found them to differ from one another in the 
most remarkable manner. 
Edinburgh, April 20. 1821. 
Art. II. — Narrative of a Descent in the Diving-Bell , fyc. <$fc. 
By Dr Louis Theodore Frederick Colladon of Ge- 
neva, Hon. Mem. R. I. A. M. W. S. &c. * Communicated 
by the Author. 
Amongst the numerous applications of the sciences to the pur- 
poses of the arts, one of the most remarkable, and at the same 
time one of the most important, is undoubtedly that which has 
carried to so high a degree of perfection the Diving-Bell, and 
by this means rendered it one of the most useful of machines, 
not only in the practice of submarine architecture at great 
depths, but in mining or exploding the rocks which obstruct the 
entrance of harbours, or in obtaining from the bottom of the sea 
any valuable goods which may have been lost near the coast. 
Having heard when I was in Ireland in September 1820 of 
the employment of this machine, which has been in use for se- 
veral years past at Howth near Dublin, and of the sensations 
experienced by those who descend to the bottom of the sea, I 
was very desirous to ascertain in person the accuracy of the 
facts which had been stated to me. It was not long before an 
excellent opportunity presented itself. Having obtained from 
my friend Mr Bald a letter of introduction to Mr Souter, en- 
gineer at Howth Harbour, I left Dublin for Howth on the 8th 
of September 1820, with a friend, intending to go down in the 
diving-bell. The weather was very fine; the wind, however, 
* Read before the Royal Society of Edinburgh, April 30. 1821. 
