0)1 the Countries of Congo and Loango. 69 
quickly effaces every vestige of fire, and makes ample amends 
for the few days in which blackness and desolation kept joint 
possession of the earth. To these annual conflagrations, and to 
the effects of the ashes on the soil, must be ascribed the civilized 
and cultivated appearance of the country. This is the harvest 
of the carrion-crow, the kite, and the vulture, which keep hover- 
ing in the rear of the flames, pouncing down upon snakes, 
lizards, crabs, &c, destroyed by the fire ; and, as already men- 
tioned, the Boa Constrictor itself, which fears no other enemy, 
frequently falls a victim to the fury of this irresistible foe, and 
becomes the prey of these rapacious birds. 
(To he continued.) 
Art. XI. — Observations on the Difference of Level qf the East 
and West Seas. By John Robison, Esq. F. R. S. E. In a 
Letter to Dr Brewster. 
Dear Sir, 
On looking over some old numbers of Thomson’s Annals, my 
curiosity was excif:ed by the statements which appear in the fol- 
lowing extracts. 
In the number for September 1816, p. 168. Dr Thomson, 
speaking of Birmingham, says : “ Its elevation has been well 
ascertained, by means of the numerous canals which proceed 
“ from it in all^^irections, and afford a level both to the east and 
west coast. It must be observed, however, that the height 
‘‘above the level of the sea, as determined by canal-locks, is 
“ not to be implicitly depended on ; for, according to the data 
“ furnished by the canals, the Irish Sea is 50 feet above the Ger- 
“ man Ocean ; but 50 feet is certainly far beyond the truth 
* In the same page there occurs this passage : “ Barbeacon, a conspicuous 
spot about eight miles north of Birmingham, is 750 feet above the level of the 
Thames at Brentford. Mr Creighton determined its height above Birmingham 
“ by levelling: he found the height, as given by the authors of the Trigonometrical 
“ Survey, deviates no less than 150 feet from the truth.” The well known scru- 
pulous accuracy of the operations, of the survey, and the talents of Mr Creighton, 
make it likely that there is some misapprehension in this statement. 
