ing the geodetic latitude to be accordant with the
astronomical latitude, the result for aberration appears to be
sensibly the same as with ordinary telescopes.--Several years since, I
prepared a barometer, by which the barometric fluctuations were
enlarged, for the information of the public; its indications are
exhibited on the wall, near to the entrance gate of the Observatory. A
card is now also exhibited, in a glass case near the public barometer,
giving the highest and lowest readings of the thermometer in the
preceding twenty-four hours.--Those who have given attention to the
history of Terrestrial Magnetism are aware that Halley's Magnetic
Chart is very frequently cited; but I could not learn that any person,
at least in modern times, had seen it. At last I discovered a copy in
the library of the British Museum, and have been allowed to take
copies by photolithography. These are appended to the Magnetical and
Meteorological Volume for 1869.--The trials and certificates of
hand-telescopes for the use of the Royal Navy have lately been so
frequent that they almost become a regular part of the work of the
Observatory. I may state here that by availing myself of a theory of
eyepieces which I published long since in the Cambridge Transactions,
I have been able to effect a considerable improvement in the
telescopes furnished to the Admiralty.--The occurrence of the Total
Eclipse of the Sun in December last has brought much labour upon the
Observatory. As regards the assistants and computers, the actual
observation on a complicated plan with the Great Equatoreal (a plan
for which few equatoreals are sufficiently steady, but which when
properly carried out gives a most complete solution of the geometrical
problem) has required, in observation and in computation, a large
expenditure of time.--My preparations for the Transit of Venus have
respect only to eye-observation of contact of limbs. With all the
liabilities and defects to which it is subject, this method possesses
the inestimable advantage of placing no reliance on instrumental
scales. I hope that the error of observation may not exceed four
seconds of time, corresponding to about 0.13" of arc. I shall be very
glad to see, in a detailed form, a plan for making the proper measures
by heliometric or photographic apparatus; and should take great
interest in combining these with the eye-observations, if my selected
stations can be made available. But my present impressi