OF LAND AND WATER ON THE SURFACE OF THE GLOBE. 293 



after they liave been once separated from the whole. To cut up the 

 plates with due care is the work of many days; if suspicion occurred 

 of any part being mislaid, or lost, it would be, in such a mass, im- 

 possible to obtain any satisfaction of the truth; and when a number 

 of small islands or lakes were to be cut out and distributed, they 

 could hardly be recovered, if it should be wislied, from tiie divisions 

 in which they had once been placed. These are not imaginary diffi- 

 culties. We must suppose that the precaution would in this case be 

 taken of ascertaining in the first instance the weight of the whole, 

 and if the sum of what was found for the parts should not be equal 

 to it, there would remain no possibility of determining the cause of 

 error: there might be a deficiency, and there would be no means of 

 discovering whether it was to be assigned to the land or to the water, 

 or to both. But even if all this could be provided against, there 

 would still be an essential obstacle in the different degrees of humidity, 

 which would be imbibed by the several parts of so many pieces of 

 paper, which could not all be equally exposed to the air. These 

 difficulties were almost entirely avoided by the careful and distinct 

 examination of each piece, and the further advantage was gained, that 

 not only the ratio might by this means be determined for the whole, 

 but, as it had been settled in detail, the corrections from future dis- 

 coveries may, at any time, be introduced, without the necessity of 

 repeating the entire examination. 



The gores of Mr Addison's globe are made each for 15 degrees of 

 longitude, and there are five divisions of each for the five zones. The 

 twenty-four for the torrid zone were cut into two at the equator, and 

 examined in forty-eight portions, in order to have the quantities for 

 each of the hemispheres. The forty-eight gores for the two temperate 

 zones, when added to these, make up ninety-six, which may be con- 

 sidered as having been analysed with tolerable completeness. In one 

 or two instances the precise terminations of land and water were of 

 necessity assumed in an arbitrary manner, but this was to a very 

 limited extent, and could not materially afFect the general conclusion. 

 In the polar circles there is a much greater degree of uncertainty, 

 and for these it was necessary in some parts to have recourse to con- 

 jectural estimates. The southern was taken as consisting entirely of 



PP 2 



