THE MUSEUM. 



241 



been done to a much greater extent 

 than most people are aware. We 

 rhave maps of Asia and Africa and Aus- 

 tralia in which the topography of these 

 ■countries is clearly described, yet act- 

 ual survey of these countries has done 

 little except to corroborate theories al- 

 ready advanced, and to furnish data 

 for the making of more minute calcu- 

 lations. 



Travelers' tales are not always ac- 

 curate and are often wholly unreliable, 

 even when there is no intention to ex- 

 aggerate or misrepresent. Such re- 

 ports form the bas'.s of gengraphy, and 

 when incorrect reports are accepted as 

 being correct, then it follows that our 

 geography is incorrect, and likewise 

 the deductions which we have made 

 and based upon incorrect statements 

 must also be incorrect. Errors, the 

 result of incorrect or incomplete or ex- 

 aggerated information, do occasionally 

 occur; but such errors, when detected, 

 only serve to add to our information 

 and to make us more careful in the 

 future. 



Thus, in the present paper in which 

 I have endeavored to describe the con- 

 figuration of the Antarctic continent, 

 although I have been obliged to be 

 guided by the statements of a few 

 travelers, I have accepted only those 

 which I believe to be trustworthy and 

 reliable. If they are so my description 

 will be found to be correct. If I have 

 been imposed upon my description may 

 be incorrect to the extent of the im- 

 posture. 



Meteorologists, all over the world, 

 have for years been recording the tem- 

 perature of various places on the 

 earth's surface. So numerous have 

 been the observations of this nature 

 that at the present time there is hard- 



ly a town of any si;^e in the world of 

 which there is not a record of its daily 

 temperature, extending over a period 

 of from one to fifty or more years. By 

 a simple mathematical calculation the 

 average temperature may be found, 

 and this, for any given locality, varies 

 but little from one year to another. 

 Not only this but every ship that sails 

 upon the ocean carries a thermometer, 

 which is used in connection with its 

 barometer, and several hours each day 

 the temperature is accurately recorded, 

 together with the latitude and longi- 

 tude of the place of observation. By 

 the comparison of records of thousands 

 of voyages we are able to construct a 

 tolerably accurate chart of the mean 

 annual temperature of the ocean. 

 Next we connect, by lines drawn upon 

 the chart, all places having the same 

 mean annual temperature. These 

 lines are called isotherms; and, for 

 convenience, each one is numbered ac- 

 cording to the temperature of the 

 places which it connects. Thus, the 

 isotherm which connects the places 

 having a mean annual temperature of 

 forty degrees is called the fortieth iso- 

 therm. Now it will be noticed, from 

 the numbers of the isotherms, that the 

 temperature constantly decreases, with 

 something like regularity, as we go 

 from the equator towards the poles; 

 and the statement that the Antarctic 

 continent possesses an intensely cold 

 climate will need no further demon- 

 stration. 



But the isotherms tell us muck 

 more. It will be noticed, in studying 

 an isothermal chart, that, when they 

 are not deflected by local influences, 

 the isotherms encircle the globe, lying 

 parallel with, and co-incircling with 

 the parallels of latitude. It will also 



