21 
porpoise with its comparatively bluff figure head we may 
surely expect a much higher velocity in the case of fish 
more obviously designed for speed. 
My son tells me that in a voyage of the ‘ Malvina ’ from 
Leith to London he had observed at night two fishes of 
about a yard long, which kept for a considerable time in 
advance of the cutwater of the ship, being visible by their 
phosphorescent light. The ship was at the time steaming 
at the rate of 15*2 statute miles per hour. 
The investigation of the resistance of solids moving in 
fluids has been taken up theoretically by Thomson, Stokes, 
Rankine, and practically by F roude, who has found that the 
surface friction in long iron ships is more than 58 per cent 
of the whole. Froude recognized the study of the forms of 
animal life in guiding us to practical conclusions. 
From the above considerations I am inclined to believe 
that a length of not more than five to one of breadth would 
be better than the extreme proportions of ships now in. 
vogue, and that the greatest breadth should be considerably 
in advance of the midship. 
“On the Coffee Leaf Disease of Ceylon, illustrated by 
preparations for examination under the microscope,” by 
H. Marshall Ward, B.A., Fellow of Owens College. 
Communicated by Prof. Osborne Reynolds, F.R.S. 
Mr. Ward commenced by sketching shortly the history 
of the coffee leaf disease, from its discovery in Ceylon, in 
1869, to the present time, and gave some figures showing its 
effect on the exports of coffee. He then proceeded to describe 
the symptoms by which the disease is recognised. 
The normally dark-green, laurel-like coffee leaves become 
spotted with yellow blotches, which arise as pale, minute 
spots on the under side, soon spreading in a centrifugal 
manner, and showing through above. Each spot becomes 
darker with age, and multitudes of minute yellow spores 
