784 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
means of control, and subcritical or diffuse illumination, as obtained by 
racking the condenser a little out of focus, is preferable and more 
commonly employed. 
While the lamp can be readily maintained at full incandescence by 
the current from an eight-cell storage battery, the care of this latter is 
by no means an insignificant matter, and Dr. Piffard is not prepared to 
recommend its use unless one has access to a street circuit. In New 
York they have both the Edison circuit with a pressure of from 110 to 
120 volts, and the alternating current distributed to houses under the 
pressure of 55 to 60 volts. If the lamp was connected 
directly with either of these circuits it would be in- 
stantly destroyed unless the pressure was neutralized 
by the introduction of suitable resistance. This was 
accomplished on the Edison circuit by the interposition 
of a 100-candle power, 100 volt, 3-amp^re lamp of the 
“ municipal ” type, the two lamps being in series. Both 
lamps will, when thus arranged, burn at full incan- 
descence ; and the large lamp can be covered up if not 
desired. 
In photomicrography Dr. Piffard has used nearly 
all the methods of artificial illumination, including the 
arc, calcium, Welsbach gaslight, and oil, but the lamp 
described was found infinitely more convenient and 
amply efficient. 
For ordinary work and for the study of absorption 
spectra by means of artificial light, this lamp is said to 
be an ideal illuminant. 
New Mounting Table.* — Mr. W. N. Preston in 
describing his mounting table, says that it is intended 
to aid the microscopist in putting up uniform mounts. 
“ A circular brass plate, 6 in. in diameter, turned per- 
fectly flat on top, is set on three legs having levelling 
screws at the bottom. This table may be set over a Bunsen burner or 
alcohol lamp and kept warm while working. 
The figure (fig. Ill) shows a plan of the top, laid out in four sections, 
by placing the three pins, 1, 2, 3 (which are set in sockets and may be 
changed at pleasure or removed altogether), in the holes opposite the 
single set of circles and laying a slide against them, an object and its 
cover-glass may be exactly centered on the slide. 
By using the set of double circles two objects may be set at equal 
distances from the centre and covers accurately placed ; likewise the 
triple set, when three are wanted on a slide. 
The first section is for cover-glass mounts, the cover being laid in 
the elevated socket A, object up ; the slide, guided by the outer pins, is 
gently lowered till it touches the drop of balsam, the two shorter pins 4 
and 5 holding it level with the top of the socket. 
At the suggestion of my friend Mr. Summers, to whom I am indebted 
for many ideas in this table, I intend having a semicircular piece of 
* Proc. Amer. Micr. Soc.,,xiv. (1893) pp. 150-1 (1 fig.). 
Fig. 110. 
