ARCTOWSKL VOLCAXIC DUST VEILS 153 



1902 and even more so in 1903. The continuous observations of Mt. 

 Colima made at the Zapatlan Observatory^^ from 1893 to 1905 give, for 

 the years 1900 to 1904, the following frequencies of days during which 

 eruptions designated "erupcion grande" have been recorded: 15, 41, 37, 

 101, 2. According to C. G. Abbot,^^ a photograph taken on ^larch 7, 

 1903, shows a column of ashes reaching an altitude of about 17 miles. 

 This figure is a simple estimate and may be exaggerated. 



On May 7, 1902, La Soufriere, St. Vincent, was in violent eruption. 

 ^•'The particular feature of this eruption was the enormous amount of 

 dust which was thrown into the air and distributed over a vast, somewhat 

 elliptical area. . . . The British steamship Toya^ had an eighth of 

 an inch of volcanic dust from this volcano fall on her deck when she was 

 two hundred seventy-five miles east-southeast of St. Vincent.'' ^^ On 

 May 8, 1902, a sea of fire destroyed St. Pierre, Martinique. The follow- 

 ing violent eruptions of Mt. Pele occurred on May 20 and 2Q, June 6, 

 July 9 and August 30. 



The influence these eruptions may have had on the thermal trans- 

 parency of the higher atmospheric layers is questionable. The excellent 

 photographs taken by A. Lacroix^^ show indeed that the occasional blasts 

 of incandescent gases and ashes did not exceed an altitude of 4,000 m. 

 Only an extremely small portion of the projected pulverized ashes must 

 liave reached the average altitude of the cirrus clouds or even the strato- 

 sphere. This may not have been the case in the violent eruptions of the 

 Santa Maria volcano, in Guatemala. The eruption began on October 24, 

 1902. An eye-witness writes : "During the first four days of the eruption 

 no view could be had of the rising crater-cloud from the immediate 

 vicinity of the volcano. Only at a distance of forty miles to the north 

 and east could the erupted sand and smoke be seen against the sky. . . . 

 Two days later I had another opportunity to view the eruption from a 

 distant hill under a clear sky, and in the day. The appearance then was 

 as follows : The peak of Santa Maria was sharply delineated against the 

 sky. To the westward or oceanward of this pyramid rose every few 

 minutes immense masses of globular clouds, like steam and smoke thrown 

 out of a locomotive when it first starts. The clouds rose to a heio^ht of 



^ S. Diaz : Efemerides del volcan Colima. Mexico, 1906. 



-■^ C. G. Abbot: "Do Volcanic Explosions Affect our Climate?"' Nat. Geog. Mag., vol. 24, 

 p. 181. 1913. 



.losfi Maria Arreola : "Brief Notice of the Observations of Colima," Jour. Geol., vol. 

 11. p. 751. 1903. 



^ Edmuxd Otis Hovey : "Martinique and St. Vincent; a I'relirainary Report upon the 

 Eruptions of 1902." Bull. Am. Mus. Nat. Hist, vol. 26, p. 333. 1902. 



^•^ A. Lacroix : La montagne Pelee et ses eruptions. Paris, 1904. 



