190 Prof. Hennessy on Terrestrial Climate as 



regions, instead of a concentration of land in the former), but 

 the study of the present relations of sea and land seems to 

 strongly verify the views on which this conclusion is based. 



If we look over a terrestrial globe, or a good stereographic pro- 

 jection of its surface*, we soon perceive that in the regions tra- 

 versed by the ecliptic, and where, consequently, the sun's rays 

 diffuse the greatest amount of heat over absorbing substances, 

 land and water are distributed very evenly at both sides of the 

 equator. Each hemisphere absorbs the greatest quantity of solar 

 heat during the six months when the sun is vertical over some 

 part of its surface ; and I have found that the parallel of 7° 24' re- 

 ceives the maximum amount of sunshine during the summer 

 half year. In the northern hemisphere this parallel runs from 

 the coast of Guinea through central Africa ; crossing the Indian 

 Ocean, south of Cape Comorin, it passes through Ceylon across 

 Malacca and the island of Mindano; thence through the Pacific, 

 until it meets South America, the northern portion of which it 

 traverses from a point near the Gulf of Panama to another be- 

 tween the mouths of the Orinoco and Esiquibo. In the opposite 

 hemisphere, the parallel of maximum southern sunshine crosses 

 Africa from a point north of St. Paolo de Loando to another near 

 the Monfeca islands. It traverses a great part of Java, New 

 Guinea, and smaller islands. It ci'osses South America almost 

 on the line of greatest breadth, from near Truxillo to a point 

 north of Pernambuco. On comparing the extent of land and 

 water lying under the parallel of maximum half-yearly sunshine, 

 it appears that the proportions are nearly the same in both he- 

 mispheres, although a very slight excess of land appears to lie 

 under the southern, compared to the northern parallel f- Outside 

 the torrid zone, the proportions of land and water belonging 

 to each hemisphere respectively are extremely different : while 

 nearly half of the surface between the pole and the tropic 

 of Cancer is land, by far the greater portion of the area 

 between the southern tropic and the pole is water. In the. 

 arctic and antarctic regions land and water alternate in nearly 

 corresponding proportions. The great difference between the 

 areas of land and water of the northern and southern hemi- 

 spheres exists in the temperate regions. Upon the whole, it 

 may be concluded that there is a comparative predominance of 

 land over water in the higher latitudes of the northern hemi- 

 sphere, while the opposite condition holds in the southern hemi- 



* M. Babinet's horaolographic maps are still better adapted for such 

 compai'isons as that now made. See Arago, Aslronomie, tome iii. p. 344 ; ' 

 Report of the British Association for 1856, Trans. Sections, p. 112. 



t See the preceding Article {Atlantis, No. 3. \\. 201 ), on the laws which 

 regulate the distribution of isothermal lines, § 5. 



