192 
NOTES AND MEMORANDA. 
the liquid to ho followed corresponding to each degree of temperature. 
The essential part of the apparatus consists of a thermometer (T), the 
“ bulb ” of which, instead of being spherical, is formed into a ring. 
The thermometer is attached to a brass plate which lies on the stage 
of the microscope, and the ring is so placed that the interspace 
coincides with the opening in the stage, and allows the light from the 
mirror to pass through it. On each side of the ring and soldered to 
it are three glass “ knobs,” to which is attached a platinum wire, 
which crosses above the ring from side to side, serving as a support 
to the preparation in conjunction with the two pieces S. This wire is 
attached at h, h, to two thicker wires of copper, which are kept in 
place by the screws at E, and when heated by a battery communicates 
the variations in temperature to the thermometer through the knobs. 
With a battery of two Bunsen elements the thermometer will register 
200° (C.), although such a temperature is not practically necessary, 
as at 150° Canada balsam boils. 
Immersion Paraholoids. — Dr. James Edmunds writes to ‘Nature’ of 
11th July : — “ The immersion paraboloid illuminator exhibited at the 
recent soiree of the Royal Society, as designed by me, proves to have 
been anticipated in principle and construction by Dr. John Barker, of 
Dublin, from whom a paper on the subject will be found in the Pro- 
ceedings of the Royal Irish Academy for 1870. An immersion para- 
boloid illuminator was also described by Mr. Wenham in the Transac- 
tions of the Microscopical Society for 1856. My paper on the subject 
appeared in the ‘ Monthly Microscopical Journal ’ for August 1877, but 
that Journal being defunct, I ask you to allow me to credit these 
gentlemen with a priority which on perusing their papers I find to be 
due to them. I ought to add that until the construction by Messrs. 
Powell and Lcaland of my illuminator, the device had never come 
into practical use, and that so far as I can learn, no reference to it 
exists in any optician’s catalogue or text-book on the microscope.” 
Organisms suspended in the Atmosphere. — M. P. Miquel has pre- 
sented through M. Pasteur a note to the French Academy on this 
subject. He says : — According to M. Charles Robin the atmosphere 
presents (besides all kinds of debris) spores, pollen, skins of insects, 
and (rarely) eggs of infusoria. According to Drs. Maddox and 
Cunningham, who have confirmed M. Robin’s results, the number of 
the different cellules distributed through the air is independent of the 
velocity and direction of the wind and of moisture. The collecting 
apparatus which Drs. Maddox and Cunningham made use of consisted 
of an aeroscope acting under the influence of the wind, and at each 
experiment the glycerined plate with which it was furnished remained 
for twenty-four hours exposed to the action of the wind. Once only 
the number of the microbia collected reached the maximum figure of 
380, after deducting all bacteroid particles. 
The results which I have arrived at after eighteen months of daily 
investigation differ in many points from those which I have just 
referred to. For the present I shall only deal with the statistical side 
of the question. 
