1815.) Philosophical Transactions, 1815, Part. 1. 221 
every alternate sector polarized in an opposite manner. 7. When. 
the erystal restores the vanished image, but allows it to vanish again 
during the revolution of the calcareous spar. Every body whicly 
possesses this kind of depolarization forms either 2 bright and a 
nebulous image, or a single image, the light of which is all polar- 
ized in the same manner. 
4, On an Elling and Flowing Stream, discovered ly boring in 
the Harbour of Bridlington. By John Storer, M.D.—In the year 
1$1} a boring was made in the harbour of Bridlington, in order to 
ascertain the thickness of the bed of clay which constitutes its 
bottom. ‘The workmen having bored through 28 feet of very solid: 
clay, and afterwards through 15 feet of a cretaceous flinty gravel of 
a very concrete texture, the auger was perceived to strike against 
the solid rock, As they were unable to make any impression upon 
this rock, the work was given up for that tide, without any appear- 
ance of water. ut the pit gradually filled with fresh water; and 
when the tide rose within 49 or 50 inches of the mouth of the bore, 
this water overflowed, and continued to do so till the tide had ebbed 
so as to be 49 or 50 inches below the mouth of the bore. This pit 
was aiterwards converted into a well, and it continues to overflow 
with the same regularity as at first. Mr. Milne, Collector of the 
Customs at Bridlington, has formed the following theory to account 
for this curious phenomenon. The bed of clay, he conceives, ex- 
tends to Smithwick sand, which forms a bar aeross the opening of 
the bay, about four miles from the quay in a south-easterly direc- 
tion. ‘Phe rain water which flows below this clay cannot be dis- 
charged till it arrives at the ledge of rocks where the clay termi- 
nates. Its issue will meet with more or less resistance according to 
the depth of the sea water. Hence the reason why the well over- 
flows every tide. here is a cireumstance which Dr. Storer thinks 
militates egainst this hypothesis. After great rains, the column of 
spring water is elevated, and the discharge prolonged during each 
tide. He thinks the subject might be elucidated by a more perfect 
acquaintance with the peculiarities of the springs on this part of the 
coast which are called gipsies. 
5. Onthe Effects af simple Pressure in producing that Species of 
Crystallization which forms two oppositely Polarized Images, and 
ldhits the complimentary Colours by Polarized Light. By Dr. 
Brewster.—Tbe author found that calf’s-foot jelly and isinglass, 
when first gelatinized, did not possess the property of depolarizing 
light; but they gradually acquired it by keeping, and immediately 
by pressure between two plates of glass. 
G. Experiments made with a view to aseertain the Principle on 
which the Action of the Heart depends, and the Relation which 
subsists between that Organ and the Nervous System. By A. P. 
Wilson Philip, Physician in Woreester.—From these experiments 
it appears that the brain or spinal marrow, or both of them, may 
ba removed from the body, or destroyed slowly, without impeding 
the aetion of the heart, provided artificial respiration be kept up ; 
