NO. 29 VOLCANOES AND CLIMATE ABBOT AND FOWLE 1/ 



normal. On the other hand, a measurement of the total intensity 

 of the solar radiation made at this Observatory in Washington on 

 October 15, 1902, gives a value of the intensity of 1.40 calories 

 per square centimeter per minute, which is among the very highest 

 observations of this kind which have been made at this station. It 

 is of course possible, though unlikely, that the haze due to the erup- 

 tion of Mount Pelee was not so quickly distributed towards the more 

 northern latitudes as that of Mount Katmai in Alaska was thio 

 year towards more southerly ones, so that perhaps the effect reached 

 Washington later than October 15, 1902. However, there were 

 other volcanoes active about this time. 



On October 24, 1902, there occurred the eruption of Santa Maria 

 in Guatemala. The ashes from this volcano covered an area of more 

 than 125,000 square miles. Pumice stone and ashes fell to a depth 

 of eight inches or more in a region extending over about 2,000 

 square miles, within which the houses and farm buildings were 

 crushed under the weight of the ejected material, and in some cases 

 totally destroyed. Six thousand persons are believed to have been 

 killed. The cloud from the volcano reached 18 miles in height and the 

 sound of the explosion was heard at Costa Rica, 500 miles away. 

 The whole side of the mountain was blown away, exposing a cliff, 

 nearly perpendicular, 7,000 feet in height, and forming a crater three- 

 quarters of a mile wide, seven-eighths of a mile long, and 1,500 

 feet deep. 



In February and March, 1903, not less than 12 maximum eruptions 

 took place from the very high and beautiful volcano of Colima in 

 southern Mexico (altitude about 13,000 feet). 1 A photograph 

 taken on March 7 shows the column of smoke projected to a height 

 of about 17 miles. 



From these records it seems to us probable that the decreased 

 solar radiation of 1888 to 1893 was caused by the volcano of Bandai- 

 San supplemented by Mayon, Vulcano Island and others, and that 

 the depression of solar radiation whose maximum was in 1903 may 

 be attributed to the volcano of Santa Maria in Guatemala, supple- 

 mented by that of Colima in Mexico. 



Observations were made in 1901, 1902 and 1903 at the Astro- 

 physical Observatory in Washington on the transmission of the 

 atmosphere for different wave lengths. We take the following data 

 from a summary of these measurements published by Mr. Abbot in 

 I903- 2 



1 See Journal of Geology, Vol. II, for a finely illustrated description. 



2 Smithsonian Miscellaneous Collections (Quarterly Issue), Vol. 45, p. 79. 



