Professor Clifton exhibited an instrument devised by him 
for observing the phenomena of Conical Refraction, both 
internal and external. 
The following letter was received on May 12th, 1863 : — 
HISTORY OF STEAM NAVIGATION. 
To the Secretary of the Literary and Philosophical 
Society of Manchester. 
Sir, 
(1.) I regret that my having been acquainted with the 
abstract only of Mr. Dyer’s paper, and not with the entire 
paper, should have led me to suppose erroneously that Mr. 
Dyer had overlooked the claims of Henry Bell, and also that 
he had mentioned Symington’s steamboat of 1801 more 
slightly than he really had done. 
(2.) With regard to the bad pecuniary result of Bell’s 
undertaking, I think it is to be ascribed to competition rather 
than to want of encouragement. In little more than a year 
after the “Comet” began to ply, a rival steamer of greater 
size and power was started on the Clyde, and was soon 
followed by others. 
(3.) In supporting the opinion of Mr. Woodcroft, that the 
title of the “ first practical steamboat” is due to that vessel 
in which the double-acting cranked steam engine — in short. 
Watt’s rotative engine — was first applied to drive the pro- 
peller, I proceed on the principle, that to constitute a “ prac- 
tical” machine, that machine must be capable, not merely of 
working well during a series of experiments, but of continuing 
to work well for years, with ordinary care in its management 
and repairs. 
