1887.] MICROSCOPICAL JOURNAL. 179 
colorless, perfectly transparent, but not without some trifling inclusions and faults. 
The form of the crystal is unusual. Professor Hanks has found such a one described 
or figured in books. The general form, as shown by examination, is that of a regular 
octahedron, but the faces seem convex. The whole crystal assumes a somewhat 
spherical form, and the edges of the pyramids are channels instead of planes, but on 
closer examination it will be seen that the channeled edges, the convex faces, and the 
solid angles are caused by an apparently secondary building up of the faces of a perfect 
octahedron, and for the same reason the girdle is not a perfect square, but has a 
somewhat circular form. These observations were well shown by drawings showing 
in enlarged form the outlines of the gem. The faces seem to be composed of thin 
plates overlying each other, and each slightly smaller than the last. These plates are 
triangular, but the lines forming the triangles are curved, and the edges of the plates 
themselves are beveled. Mr. Hanks remarked further that it could be seen by the 
enlarged crystal shown under the microscope and by drawings exhibited that each 
triangular plate was composed of three smaller triangles, and that all the lines were 
slightly curved. The building up of plate upon plate causes the channeled edges and 
the somewhat globular form of this exquisite crystal. The sketches shown were made 
from the diamond while in the field of the microscope by the aid of the camera-lucida, 
being enlarged about ten diameters. 
A close examination of the crystal revealed tetrahedrai impressions as if the corners 
of minute cubes had been imprinted on the surface of the crystal while in a plastic state. 
These are the result of the laws of crystallography, as were seen by the faint lines 
forming a lace-work of tiny triangles on the faces when the stone is placed in a proper 
light. Professor Hanks concluded with the remark that it would be an act of vandalism 
to cut the beautiful crystal which is a gem in two senses, and he protested against 
its ever being defiled by contact with the lapidary’s wheel. 
The diamond was placed under the microscope and arranged by Professor Hanks 
to demonstrate the points of his very accurate description. It was a beautiful object 
and was admired by all present. 
Dr. Riehl, of Alameda, gave a demonstration of discovering tubercular bacilli in the 
sputum of consumptives. He proceeded with the operation of staining, decolorizing, 
etc., and finally showed the minute germs clearly under the lens. Dr. Riehl made no 
claim to originality in the method employed, but showed how he handled the material 
so as to disclose the bacilli quickly for purposes of diagnosis. Discussion ensued as 
to the value of different methods, Dr. Ferrar and Dr. Mouser maintaining the value 
of the careful and exact methods of procedure laid down by the German investigators 
for purposes of exact determination. Dr. Mouser showed a very handsome piece of 
apparatus called ‘Schlessing’s Thermo Regular’ which he had just received from 
Germany. Itisto be attached to the incubator used in cultures of bacilli, etc., in such 
a way that the water of the incubator comes in contact with the rubber plate of the 
regulator and expands it. This expansion of the rubber presses upon the other parts 
in contact with it and partly closes the pipe, admitting gas to the jets which heat the 
incubator. The appliance is so delicate that an elevation of one-tenth of a degree in 
the heat will act upon the gas flame and reduce it. 
President Wickson exhibited a specimen of sonorous sand sent to Professor Hilgard 
by W. G. Thompson, of Pescadero, and referred to him for examination. Mr. Thomp- 
son's letter explained that the sand when driven over or walked on, or even disturbed 
with a stick or with the hand, gives out a distinct musical sound. Perhaps the strangest 
thing about it is that the persons longest in the vicinity of Pescadero seem not to know 
of the existence of sucha place. lt is away from the usual places of resort. The 
much-talked of ‘singing beach’ of Manchester, Mass., is only one-fifth of a mile long, 
while Mr. Thompson has traced this sand at Pescadero along the beach for over a mile 
and ahalf. Mr. Wickson remarked that the subject of sonorous sand had been before 
the society some years ago in connection with specimens sent from the Sandwich 
Islands and had been studied by Professor Hanks. The society’s cabinet contains a 
slide of the Sandwich Island sand. The Pescadero material would be studied in the 
light of these facts, comparisons made, and the subject presented at a subsequent 
meeting. Specimens of the sand were distributed to those present. 
J. Z. Davis showed a sample of kelp from the southern coast covered with minute 
shells of mollusca so that the green kelp seemed almost white. The subject was 
referred to Dr. H. W. Harkness with the request that he report at a subsequent meeting. 
The society then adjourned. C. P. BATES, Secy. pro tem. 
