376 On a Temporary Outburst of Light [July, 
a horizontal tunnel from the Park pit at a depth of 200 yards 
from the surface; “beyond this, Coal-measure shales and clays 
with Stigmaria were proved, and the tunnel was left off in a red- 
ae grit, similar to those found in the Coal-measures of Denton and 
yde.” 
It is from private enterprizes of this nature that the area of our 
workable coal-seams will become extended as the geological sur- 
veyors make us acquainted with the exact structure of the districts 
bordering our known coal-fields ; but there is a more speculative kind 
of “ prospecting ” which we venture to think is a more fit, though a 
much more novel, subject for national expenditure than a great 
many others, including even expeditions to the North Pole. We 
refer to the probability of coal existing at no enormous depth 
beneath the Tertiary and Cretaceous deposits of the south-east of 
England, just as it is known to do beneath the chalk of Valen- 
ciennes, where it has been extensively worked; and of Calais, 
where it has been reached by borings. Geologists have even 
mapped the probable direction and extent of the subterranean pro- 
longation of one of our great coal-fields ; but opinions are divided 
as to the particular English coal-field with which the French (and 
therefore also the hypothetical London) field is connected. Mr. 
Godwin-Austen, who first started the notion of a London coal-field, 
considers it to be connected with the South Welsh and Midland 
coal-basins ; but others hold the balance of probabilities to be in 
favour of the Northern coal-field. It would cost the nation com- 
paratively little to demonstrate, by boring, the correctness or error 
of one or both of these views; and if coal were won, the expense 
might easily be defrayed, and a large source of revenue created, by 
a tax on the consequent yield. 
VITI—ON A TEMPORARY OUTBURST OF LIGHT IN 
A STAR IN CORONA BOREALIS. 
By Witu1am Hvaers, F.RBS. 
OccasIONALLY, but at rather long intervals, men have been startled 
by the extraordimary spectacle of the sudden appearance of a 
brilliant star in a part of the heavens where before no star was 
to be seen. 
During the first seventeen centuries of the present era, perhaps 
eight or nine of these strange visitants astonished the world. It is 
probable that many of the objects in the Chinese catalogue of Ma- 
tuan-lin are not stars, but, as their observed motion appears to show, 
