Natural Philosophy. — Optics. 36^ 
below low- water-mark. From this pipe is brought another, 
like those for distributing gas, terminating in a well closed reser- 
voir, provided with a little forcing springe, and with an open ba- 
rometer gauge, to which may be added, if necessary, a mano- 
metrical gauge. Before each observation, the syringe should 
be worked till the gauge becomes stationary, by the escape of 
the air under the water, so that the column of compressed air 
may always begin from the level of the upper angle of the tri- 
angular orifice ; the height of the gauge will then obviously in- 
dicate the height of the surface of water above this level.— 
Quarterly Journal of Science ^ No. S2. p. 348. 
OPTICS. 
5. Unusual Parhelia seen at the Cape. — On the 7th May 
18S3, when the sun’’s lower limb had just dipped the water’s 
edge, the Reverend Mr Fallows observed several parhelia, viz. 
4 on the left, and 3 on the right hand of the sun, and all cut 
by the horizon like the real sun. They had the same shape as 
the real sun, and were as high, but not so long. When the 
upper limb of the sun came in contact with the horizon, it and 
the mock suns appeared as bright points upon the water’s edge, 
and then one of them instantaneously vanished. The barome- 
ter was at 30.2 inches, and the thermometer at 64®. Dr Young 
supposes that these parhelia were ovL\y fragments of coronae^ form- 
ed by the diifraction of a cloud rising but little above the hori- 
zon ; and he attributes the absence of colours to the absorption 
of all the light except the red, in its long passage through a 
hazy atmosphere. 
The phenomenon now described we consider as very remark- 
able, and as one hitherto unobserved ; but we cannot, for the 
following reasons, concur in the ingenious explanation of it 
given by Dr Young: 
1. Mr Fallows distinctly states that not a cloud was visible. 
2. He distinctly describes, and draws the mock suns as hav- 
ing exactly the shape of the real sun, — a form which fragments 
of coronse could not be supposed to assume. 
3. He describes them as equal in brightness to the real sun, 
lyhich they could not possibly be, if they were fragments of co- 
