ASTRONOMICAL PHENOMENA AND PROGRESS. 



35 



appeared to grow worse. But in the latter 

 part of the year several statesmen were called 

 to the management of public affairs who en- 

 couraged the hope for an era of reform. 



In consequence of a treaty between the 

 Netherlands and England, concluded on Feb- 

 ruary 5, 1871, and the additional articles agreed 

 upon on November 2, 1871, the English Gov- 

 ernment relinquished all the reservations rela- 

 tive to the further extension of the Dutch rule 

 in Sumatra which were contained in the treaty 

 of March 17, 1824. In return, British subjects 

 in the state of Siak-sri-Indrapoor, and in ter- 

 ritories dependent upon it, obtain the same 

 rights with regard to commerce and navigation 

 as the Dutch subjects, and they will obtain 

 the same rights in every other state which 



may become subject to Dutch rule. But all 

 their laws concerning persons of Western 

 and Eastern descent will remain in force, as 

 well as the provisions of the agreement of 

 1851. 



The political changes which have occurred in 

 Asia of late, especially the Russian conquests, 

 and the many new explorations, have consider- 

 ably ^modified the frontiers of the countries in 

 the interior of Asia. Some of the countries 

 have as yet no definite regulation of their 

 boundary-lines. The following statement of 

 the area and population of the divisions and 

 subdivisions of Asia, based on the latest ex- 

 plorations and calculations, are as follows 

 (Behm und "Wagner, "Bevolkerung derErde," 

 Gotha, 1872) : 



ASTRONOMICAL PHENOMENA AND 

 PROGRESS. Tlie Supply of Solar Heat. 

 Captain John Ericsson, the distinguished phys- 

 icist and inventor, continued, during the year, 

 to contribute papers to the scientific publica- 

 tions of England, in further discussion of the 

 source and permanency of solar energy. The 

 experiments upon which his calculations are 

 based were briefly set forth in the ANNUAL 

 CYCLOPEDIA for 1871. Helmholtz had esti- 

 mated the shrinkage of the sun's diameter at 

 Toyro i n the course of 2,000 years. Captain 

 Ericsson revises the calculation, and makes 

 the period of that amount of shrinkage 1,864 

 years, or 120.7 feet per day. He observes 

 that the intensity of the radiant heat will not 

 diminish with the diminished size of the sun. 

 On the contrary, for a given area of the solar 

 surface, the dynamic energy produced by a 

 given rate of shrinking will be increased, 

 since the mass remains the same, while the 

 attraction is increased proportionally to the 



square of the distance from the centre. But 

 the rate will diminish with the contraction of 

 the sphere ; hence, a shrinking of xoth the sun's 

 diameter, instead of occupying 1,000x1,864= 

 1,864,000 years, will require somewhat more 

 than 2,000,000 years. At the end of that 

 period, the gravitating energy will continue 

 to develop, as at present, an amount of dy- 

 namic energy represented by 312,000 thermal 

 units per minute for each superficial foot ; but 

 the radiating surface, i. e., the area of the solar 

 disk, will have diminished in the ratio of 10 2 

 to 9 . The present maximum temperature, 

 produced by solar radiation on the ecliptic, 

 when the earth is in aphelion, being ^7.2, 

 while the intensity of the radiant heat dimin- 

 ishes as the area of the radiating surface, it 

 follows that, at the end of 2,000,000 years 

 from the present time, the tropical solar inten- 



9 2 x 67 2 

 sity will be reduced to = 54.4, un- 



