258 TIic Anicricaii Geologist. October. 1900 
The hydrographic engineers have endeavored to note accurately 
during 1877-QQ the inflow, outflow and loss by evaporation of botli lakes 
Managua and Nicaragua connected by the Tipitapa river. At times 
there were unfortunately some careless men in employ of the Interoce- 
•anic Canal Commission, hydrographic division, until Mr. A. P. Davis 
discharged them as soon as he discovered their inefficiency. 
The aqueous condensation is not represented in full by the rainfall. 
This aqueous condensation other than the rainfall is affected by varia- 
tions in temperature the same as is the evaporation: evaporation is 
caused by currents of dry winds and the heat during the day, whereas 
the fall in temperature of several degrees during the night causes the 
condensation of the aqueous vapors from the oceans to a cjuantity worth 
estimating. 
If between i&8oand i8q8, there has been a decline of 20 feet from 
the 1880 level of fake Nicaragua from any cause, then the beach marks 
of the j88o tevel would be easily found along the borders of the lake. 
But there is no such evidence to be found. 
There is no question of the fact that the entire American isthmus 
from Salinas bay in Mexico to the south side of Darien is subsiding 
slowly; while south of Darien on the Pacific ocean side at least to the 
straits of Magellan there is a corresponding elevation of the land, liut 
much too small annually to be generally noted. Should this subsiding 
of Nicaragua continue, the time will come centuries from now when 
the Nicaragua canal route that Prof. A. Heilprin seems to be after will 
require only a very short cut or channel, if anv, to connect the waters of 
the Atlantic and Pacific oceans. There was a time evidenced by the 
fjords on the eastern coast of Nicaragua, southern and southwestern 
Cuba and western sides of the Antilles, whenNicaragua was a continent 
extending eastwardly to at least the east side of the Antilles. Now Nic- 
aragua and the entireAmerican isthmus is sinking as above stated. 
Comparing the "rainy season" — thus far— of 1900 with previous sea- 
sons we are likely to have as much water in lakes Nicaragua and Ma- 
naga in November and December, iqoo and January, igoi as there was 
in 1880, which has been reported I am not certain but 1878 or 1880 — 
as a year when because of excessive rains, and consequently also a re- 
duced temperature and less evaporation, the water in l)oth lake Mana- 
gua and in lake Nicaragua, discharging the surplus through RioTipatu- 
pa into the latter — were 7 to 10 feet higher than ever noted in history 
before. The rainfall in July, igoo has been excessive, twenty-one tor- 
rential rains and two all-night rains in western Nicaragua; and this ex- 
cessive rainfall continues to date, August 14, igoo. 
J. Crawford. 
