446 
POPULAR SCIENCE REVIEW. 
moment of absolute time on eacli day for one or more years. After 
describing bis own (now abandoned) efforts in this direction, be stated 
that tbe amount of material collected by tbe Meteorological Committee of 
tbe Royal Society gave one hopes of tbe early production of some of 
these charts, Mr. Meldrum exhibited engraved specimens of the charts, 
and pointed out the leading features of each, showing the existence, on the 
days in question, of several revolving and other storms, and calling atten- 
tion to the fact that there was apparently a strong tendency in the wind to 
blow tangentially to the isobaric curves, but that it was only a tendency, 
the direction of the wind being generally more or less inclined to the 
isobars. In conclusion, Mr. Meldrum strongl})^ argued the importance of 
mapping the weather daily as it existed at a particular hour over extensive 
areas, that being, in his opinion, the most efficient way of solving many 
questions of great scientific and ’practical importance. Who could doubt 
that, if we had charts showing the daily state of the weather, barometer, 
&c., at a certain moment, over the North Atlantic, the continent, and the 
British Islands, for even the last twelve months, we should know much 
more than we do regarding questions of the utmost importance to naviga- 
tion ? He believed that to the practical sailor synoptic charts would be at 
least as valuable as average charts that a chart showing the winds and 
weather actually observed over a certain extent of ocean on one day of 
normal weather would be fully as trustworthy a guide as a chart showing 
the average on prevailing winds obtained from one to three months’ obser- 
vation. But however that might be, and without underrating the impor- 
tance of averages and constants, there could, he thought, be little doubt 
that meteorology would be more promoted by the synoptic or synchronous 
method than by that of averages. 
The Report of the Rainfall Committee. — This Report was brought up ” 
at the meeting of the British Association, by Mr. G. J. Symons. It is full 
of important matter, and deserves a longer notice than our space admits of. 
It offers some sound advice on the management of rain gauges. 
MICROSCOPY. 
A Camera Lucida for Vertical Use. — One so often requires to take a 
drawing of specimens freshly placed in liquid on the microscope stage, 
that it becomes of some importance to be able to employ the camera lucida, 
or tint-glass reflector, for this purpose. As the instrument has been hitherto 
arranged, this is impossible, for as^ the body cannot be inclined (since the 
specimen must be horizontal), the tint-glass reflector becomes practically 
useless. An ingenious appliance has just been manufactured by Mr. Charles 
Collins, optician, by which all the difficulty referred to is obviated. It 
consists simply in a right-angled tube containing in its angle a right- 
angled prism. The eye-piece of the microscope having been removed, this 
is fitted to the body, and in its other extremity is placed the eye-piece. 
The eye- piece is thus horizontal while the body and objective are vertical. 
The tint-glass is placed, as usual, in the eye-piece, and the instrument is 
