60 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 90 



The large correction for August, — o°8, will doubtless give 

 rise to comment. During the five years 1903 to 1907 it 

 amounted to — o°y and from 1908 to 191 2 to — o°9, so 

 whatever the reason, there is no doubt that the correction 

 of — o°8 is justified, especially as the corrections for the 

 other 11 months were more or less constant during the two 

 pentads. The observations used from 1889 to 1901 were 

 hourly, so that strictly speaking, the published values to 

 reduce to ^(7 h + I4 h + 2i h + 2i h ) should have a plus correc- 

 tion of o?i applied in some months. On the other hand, as 

 the correction to reduce any combination of hours to mean 

 of day (which is the mean sought for) is variable, it is 

 better to take hourly data when available, since factors such 

 as amount of cloud and vapor pressure render a flat correc- 

 tion more or less an approximation to the true mean, 

 especially in regions subject to variable conditions in months 

 of the same name. This can easily be proved from stations 

 for which a long series of hourly values is available. 

 Precipitation. 



The rain data from 1879 to 1883 are derived from a table in the 

 Quart. Journ. Roy. Meteorol. Soc. London, volume 11, page 

 223. From 1894 to 1912 the Normal School data were taken 

 and those at the Observatory (Avenida Paulista) since. For 

 the 10 years ended July 191 1 the average rainfall at the 

 Avenida Paulista was 1596 mm and at the Normal School 

 1 501 mm. During the rainy season (October to March) the 

 values were 1202 and 11 19 mm respectively and during the 

 other six months, 394 and 382 mm. 



IGARAPAVA 



This station was formerly called Santa Rita do Paraiso, but in 191 1 

 the name was changed to that of Igarapava. The hours of observation 

 are the same as for the other two stations. As pressure data for the 

 region are well represented by such stations as Rio de Janeiro, Cuyaba, 

 and Curitiba, it was decided that barometric data were not necessary, 

 so for this reason and to economize space, the values have not been 

 sent. Complete barometric data are available, however, for eight 

 representative stations if required. 



iguape 



The height of the station varied from 3 to 10 m. For neither station 

 is there any information as to height of the rain gage above the ground. 



