112 POPULAR SCIENCE REVIEW. 
all events well deserving greater attention on the part of the physiologist and 
medical jurist. — Allge. Wien. Zeit., 34. 
The Accommodative Power of Eye. — As recent continental inquiries have 
shown how utterly impossible it is for the ciliary muscle or processes to have 
any action on the crystalline lens, the following interesting case shows how 
much the phenomena of accommodation may depend upon the cornea or 
iris, or both. The case is given in a paper by Dr. Mackenzie, and is as 
follows : — “ As illustrating the power of distinct vision, sometimes possessed 
by those who have lost the crystalline, I may notice the instance of a gen- 
tleman, mentioned to me by Professor Allen Thomson. This gentleman had 
cataract in both eyes at rather an early period of life. He regained the use 
of one of them some twenty or twenty-five years ago, by extraction, under the 
care of the late Mr. Alexander. Employing a convex lens of about four inches 
focal length, he possesses an acuteness of vision wonderful, not merely for a 
person in his circumstances, but for any one. Always employing (as far as 
Professor Thomson recollects) the same lens, he enjoys as complete a power 
as most persons of seeing with clearness and precision near or distant 
objects. To show how minute his vision was, he wrote a long passage of a 
letter in so small a character that Professor T. found it necessary to use 
a strong magnifier to enable him to read what had been written. Professor 
T. had frequently seen this gentleman read alternately the smallest type of 
a printed book at a near distance, and the larger type of the title-page 
across a room, as well as the words of a sign-board or the names over 
shops, across a wide street. He could have no doubt whatever that his 
vision at these various distances teas just as well defined and precise as that of 
persons possessing the ordinary powers of accommodation.” — Vide Ophthalmic 
Review, No. VII., p. 227. 
MECHANICAL SCIENCE. 
Armour-plated Vessels . — The Minotaur has now been added to our iron- 
clad navy, having been launched at the end of last year, and tested during 
September of the present year. This frigate differs from the Warrior — 1st, 
in carrying the armour-plates round the bows and stern, as well as on the 
broadside ; 2nd, in having the armour-plating on the broadside 5-?r inches 
thick on 9 inches of teak backing, instead of 4^ inches thick on 18 inches 
of backing. With full boiler power her mean speed was 14*778 knots, with 
57^ revolutions of the engines, the boilers working at 25^ lbs. pressure. 
With half-boiler power her mean speed was 12*406 knots ; revolutions of 
engines, 48 ; and pressure of steam, 20 lbs. These trials were at the light 
draught of water, 23 feet forward and 24 feet aft. Compared with the 
Warrior's speed at deep draught of 14*356 knots, the speed of the Minotaur 
is so little in excess that she will probably prove the slower frigate of the 
two. The Bellerophon on her trial trip has fallen further short of the 
Warrior standard, making only 13f knots, instead of the 15 knots expected, 
the engines developing only 5,000 h. p. indicated, instead of 6,000 estimated 
by the makers of her machinery. In these trials there was found to exist a 
