NOTES AND QUERIES. 265 
sary to say, expects that cholera will prove to be due to a micros- 
copic organism. He has written a series of hygienic measures to 
be observed by the members of the mission, in order to minimise 
the danger they are about. 
AMERICAN SCIENTIFIC EXPLORATION.—The Washington, a vessel 
of the United States navy, is about to explore the basin of the Medi- 
terranean, examining its depth and temperature, the density and 
chemical composition of its waters, the geological character of the 
bottom, the swiftness, general direction, and courses of the currents, 
and their action on the coasts, and also the fauna and flora of the 
deeper portions. 
Hop VeERMIN.—The attack of vermin in the hop plantation 
seems to be pretty general throughout Kent and Sussex, though, 
happily, not to the serious extent to which many of the grounds in 
the Canterbury district have been afflicted. A good deal of alarm 
has been created by the appearance of lice at this critical period of 
the season, and many planters have resorted to washing, and the 
use of the sulphurator. With regard to the twelve acres near 
Canterbury where the presence of so much vermin was discovered, 
another inspection not only confirmed the grave character of the 
former report, but showed that the attack had become even more 
serious. Thunder showers, followed by hot sunshine, are now 
needed to keep down the insect pests and ward off blight. 
LeEITz OIL-IMMERSION ONE-EIGHTEENTH.—Mr. H. P. Aylward 
has sent us for inspection two of Leitz high-power oil-immersion 
objectives, ~.th and ;,th, they are both of N. A. 1.26. The jth 
is virtually a jth when examined by Cross’ formula, and it has the 
remarkable working distance of .or inch, working easily over every 
slide in our cabinet. Its price is, we believe, only nine guineas. 
FaLL oF STONES IN MANCHESTER.—After a severe thunder- 
storm in Manchester during the middle of June, the pavement in 
King-street was covered with small stones, supposed by some to be 
of meteoric origin. Mr. T. P. Barkas, of Newcastle-on-Tyne, has 
examined them microscopically, and the following is his report :— 
“The majority of the specimens received appear to have been 
newly fractured and consist of whin, their specific gravity being 
between 2.8 and 2.74. Several of the specimens have a glazed 
and slag-like appearance, and I infer from their structure that they 
have been subjected to great heat. It is improbable that newly- 
fractured stones having the structure of whin should fall from 
interstellar space, and the probability is that a whirl-wind at some 
distance from where the stone fell lifted and carried them over the 
localities where they descended.” 
