244 



THE ANTIQUITY OF MAN IN TASMANIA. 



ments which are generally used in the calculation of the 

 area of surfaces; I constructed therefore a network of 

 squares, each having an area of lOO nautical square miles, 

 and by means of these I could estimate the area of each 

 stage. The values so obtained I converted into ordinary 

 square miles, and this being done by logarithms, the 

 figures appear to be painfully correct, though in fact they 

 represent estimates only. Nobody will dispute that, con- 

 sidering the crude method, I might, for instance, just as 

 well have written 10,000 instead of 9,993 square miles. It 

 would perhaps have been much better had I given round 

 figures, but this would have again required all sorts of 

 corrections in order to make the aggregate of water and 

 land agree with the area of the map. I therefore pre- 

 ferred to give the figures as I obtained them, leaving it 

 to somebody better equipped than I am to obtain more 

 accurate ones. I may, however, say that a check of the 

 area of the islands which is known and the area obtained 

 by my method give a difference of only 20 square miles, a 

 result which is very satisfactory considering the crude 

 method used. 



We find that the actual increase of land for every 5. 

 fathoms changes considerably, and in the following table 

 I give it in absolute figures and in per cents.: — 



Total area of land Actual increase Per cent, of the 

 miles. sqr Miles. preceding area. 



6,916 — 



This table wants also a few words of explanation. I 

 mentioned above that the changes which take place if 

 the sea level were to recede from o to 5, from 5 to 10, 

 from 10 to 15, and from 15 to 20, are comparatively 

 small, though on the whole the receding from o to 20 

 fathoms produces an increase of the land of 6,916 square 

 miles. The average increase per 5 fathoms would 

 therefore be 1,729 square miles. It is, however, very 

 probable that the actual increase from o to 5 fathoms is 



