412 
DRS. T. ANDEKSOX AND O. S. FLETT ON THE EEUPTIONS OF THE 
instance of this is that of the barque “ Jupiter,” which was 830 miles E.S.E. of 
Barbados on May 8th at 2.30 a.m., when the dust fell upon its decks. Many of the 
records of these dustfalls are unverified,'^ but in this case there seems to be no reason 
to doulDt the accuracy of the report, as, although we did not see the dust, we met 
several people in Barbados to whom it had been shown, and they all described it as 
very similar to that which was lying on the houses of Bridgetown at the time, only 
much finer and somewhat paler in colour. 
The dust which fell in Jamaica on the 11th May is very different in composition 
and appearance from all the other volcanic dusts which we have seen. Mr. Schar- 
SCHMIDT has sent us a sample of the material which he collected, and it proves to 
consist very lai’gely of vegetable matter, pollen, Sy-cryptogamic spores, hairs and 
fragments of the cuticle of plants, desmids and diatoms. In addition to these there 
are mineral fragments which include small grains of quartz, calcite and impalpable 
inorganic dust. But there are also small, clear, almost colourless, isotropic grains, 
which show a very irregular fracture, and have no trace of organic structure. When 
the dust collected is incinerated on platinum foil at as low a temperature as possible, 
these fragments remain unchanged. We think it probable that they are pieces of 
fine volcanic glass, as they closely resemble the fine glassy splinters which can be 
found in the Barbados dust. There is no augite, no hypersthene, and, so far as we 
can say, no felspar. This is exactly what might have been expected in consequence 
of the great distance to which the mineral fragments were carried. The heavier 
would necessarily sink first and only the lighter glass would reach the limits of the 
area of distribution. None of these glassy fragments contain any microliths ; and the 
proportion of volcanic glass in the dust sent us is exceedingly small; the average 
size of the grains is '02 millim. 
This dust is quite unlike that which was collected on the decks of the “ Jupiter” 
at about the same distance from the Soufriere in an eastern direction, and shows that 
while Jamaica was near the limits of the dustfall to the west, it had a far greater 
extension to the east, so that the Soufrik’e does not stand in the centre of the 
elongated elliptical area of distribution. This is due to the persistent easterly 
currents in the upper atmosphere. It may well be the case that falls of dust took 
place over the sea to the east of St. Vincent for considerably more thon 2,000 miles 
from the island. 
Of the total amount of material ejected on the afternoon of Wednesday, Mav 7, 
* Other authenticated records of dustfalls observed on ships which were obtained by the Harbour¬ 
master of Barbados, and jmblished in the ‘ Agricultural News ’ (Barbados), June 7th, 1902, are as 
follows:— 
“May 7, 8 p.m., schooner ‘ Violo,’ from Demerara, met the dust 70 miles S. of Barbados, 10 P.M., the 
Norwegian steamer ‘ Talisman,’ from Demerara, 150 miles S.S.E. 
“ May 8. Hour not stated, barquentine ‘ Fanny,’ from Pernambuco, 250 miles E. 
“ iMay 9 {'I 8), 4 P.M., ship ‘ Monrovia,’ from Bio Janeiro, 240 miles S.E.” 
