1898 - 99 .] Admiral Makaroff on Oceanographic Problems. 405 
Petlikaie in the Arctic Sea, also records a thickness of 5 feet. 
The ice of the Kara Sea usually melts every summer, so that the 
Kara Sea is filled in winter with one year’s ice. Ice of many 
years’ duration is found in the Kara Sea only occasionally. 
Mr AfonasiefF, who is well known in English literature by his 
formulse on the resistance of ships, has worked out for me a very 
simple formula for determining the relation between thickness of 
ice and the power of the engines required to drive the ship through 
it. By this formula 10,000 horse-power is required to drive a ship 
through five feet of ice with a speed of 1 to 2 knots. 
One to two knots is not a business speed, hut it is not intended to 
navigate in the Kara Sea in winter time. The mouths of the 
Siberian rivers, Obi and Yenesei, are not clear from ice before the 
end of June, and it is no use to go with a cargo to these rivers 
before the river steamers can come to the mouth and take the 
cargo. By that time the sun will affect very much the ice of the 
Kara Sea, and surely the ice will not be as strong as in the winter 
time, and that will allow the ice-breaker to proceed at a much 
higher speed. In many places the Kara Sea would be open 
already by the middle of June, and that would again be to the 
advantage of the speed of the ice-breaker. 
Certainly, the Kara Sea is not only covered with plain ice, but 
also with pack ice, which may be of considerable thickness, but the 
effect of the sun and the under current will probably take off a 
certain part of the strength of that pack ice. The most difficult 
places are probably not far from the mouths of the Siberian rivers, 
and perhaps the greatest difficulty will be found there. Ko one 
knows how this ice is packed, and it is only by trial that one can 
inform himself upon this complicated phenomenon. It will be a 
very great success for the ice-breaker if it can come to the mouths 
of the rivers at the time when they are just opening, but if this 
should prove, at the end of June, beyond the power of the ice- 
breaker, anyhow the ice-breaker will be able to reach the mouths 
of the Siberian rivers before any other ship can venture to do so. 
It is not enough that the ice-breaker should be able to force it- 
self through the ice, but it is necessary that the ice-breaker should 
leave behind a channel through which an ordinary cargo steamer 
can pass; the channel maybe filled with the detached pieces of 
