404 Proceedings of Royal Society of Edinburgh. [sess. 
the large lakes, and the most powerful of them (“ St Maria ”) has 
two engines, both developing about 3,500 horse-power, the fore 
engine being a trifle less powerful than the stern one. 
I thought, however, that it would not he sufficient to break the 
ice only to St Petersburg. My country is barricaded by the ice 
almost from everywhere. If you look at the chart of the Arctic 
Ocean (Plate XI.), you will see that the front of my country is 
turned to the Arctic Sea, but that Arctic Sea is constantly 
covered with ice. Almost all large Siberian rivers flow into the 
Arctic Sea, the ice of which barricades the way and does not 
allow of a regular sea navigation to these Siberian rivers. Any- 
how, navigation was tried for many years, and in the month of 
August one may hope to pass safely through the Arctic Sea to the 
rivers Obi and Yenesei, but it is too irregular a route for commerce, 
and for this reason the transport of goods by this way is very 
expensive. We have other expensive means of transporting our 
goods to Siberia; what we really want is a cheap method of 
communication, because the goods that we export are cheap and 
cannot stand a high tariff. 
The only means of making navigation to the Siberian rivers 
cheap is the ice-breaker, and if it becomes possible to make navi- 
gation to the Siberian rivers sure during three or three and a half 
months a year, then it will be business-like and the tariff will go 
down, so that it will be possible to export our cheap goods, such as 
wheat and wood, which are found in Siberia in great quantities, 
and at a cheap price. 
The question is whether ice-breakers can deal with the ice of 
the Kara Sea. I do not possess exact data about the thickness of 
the ice in the Kara Sea, but one can estimate its thickness by 
theoretical calculations. We know the winter temperature at 
Novaia Zemlya, North Coast- of Siberia, and also the temperature 
observed during the Dutch Expedition of 1882. All these figures 
show that the quantity of degree days of frost may be estimated 
yearly as being a little over 4000 Centigrade. Weyprecht in his 
book gives the relation between the quantity of frost in a given 
place and the thickness of plain ice; 4000 degree days of frost 
give by his tables a thickness of ice corresponding to 5 feet, and 
Nordenskiold on board the “Vega,” during his winter close to 
