Doyvte—Rio del Fuerte of W. Mexico, and its Tributaries. 73 
APPENDIX. 
Generally the highest temperatures were observed in narrow, 
deep river valleys ; the low open plains were cool at night, but had 
a high temperature in the day; the coolest night was April 6, at 
Orochibo, elevation 7575 feet, on the mesa, when there were 19° of 
frost and thick ice on still water. There was slight cloud at sunset 
in the plains on February 6, 8, 10, 138, and 20, with very brilliant 
colouring; thunderstorms occurred in the foot-hills on March 19 
and 27, with heavy rain and small freshets in the river. At San 
Blas, on February 7, there was a dense fog in the morning, with 
minimum temperature 40°F. No other fog, cloud, or rain was 
observed during February, March, and April. 
There was a gale from the N.W. in the gulf on January 29 
and 380, with clear sky, no rain, and a heavy sea; on the coast the 
wind was fresh to strong from the west on February 1, 2, and 3. 
Inland it was generally calm, in the foothills at San Juan de Dios, 
there was a strong, hot, dry wind down the valley on February 26. 
During March and April a dead calm lay over the mountains. 
Disturbances of the barometric pressure beyond the diurnal 
oscillations are rare, readings remaining constant for many weeks 
at a time. 
The air is extremely dry ; steel articles left on the ground every 
night do not rust, and no dew is deposited, notwithstanding the 
clear sky, except at the bottom of ravines. 
[Summary or Temppratures, &c. 
