Daily globe., 1883-08-17

planet. They were taken between the four
contacts. The spectroscopic observations
had not yet been reported to the essayist.
The English observers had taken some
very valuable photographs of the eclipse
at the four contacts.
We had FIVE minutes and twenty-five Sec
onds totality. I wished to determine if
the planets discovered by Prof. Watson
could be seen. My opportunities were the
best. My apparatus were satisfactory. I
recognized every star down to the sixth
magnitude minutely. 1 swept over the
whole field carefully and there were no
new stars not down on the charts, and con-
sequently 1 am perfectly satisfied that
there are no new planets as described by
Profs. Watson and Swift, and I wish
to have the society so conclude.
There is no large planet near the sun.
The black bodies seen from time to time
upon the surface of the sun are undoubt-
edIy simply color spots.
DOUBLE CYLINDER ROTARY PUMPS.
j. Burkitt Webb presented the regularity
of flow from double cylinder pumps. The
speaker had a number of models of the
various styles of rotary pumps. The gen.
eral principles of the pumps are set of
teeth which act as piston and on the
opposite side they act as a valve. It is
not necessary that the wheels or teeth
should revolve at the same speed. It is
only necessary that they really revolve,
and that they are Of sufficient length to
closely fit the case in which they are neatly
fastened. To illustrate the theories of the
speaker, the models we're not only almost
constantly resorted to, but blackboard
work took an important part.
FLEXURE CORRECTIONS.
Prof. W. A. Rogers gave new method
of investigating the fexure corrections of
a meridian circle
The error due to refraction, the fexure
of the circle itself, the astronomical fex-
ure, the three being functions in them
selves, are the most prolific of all errors
respecting dexures of meridian circle.
The theory which suggested itself to me
was arrived at from use of tube tele-
scope and level, of a different construction
than any had ever seen. l was disbe-
lever in level but this level converted
me into an advocate of the level. The
principal tube is attached to plate, and
the plate attached to the tube of the tele-
scope. You can then set the telescope at
the north point, or reverse it to the
south, and the change during
the reversal loses nothing of correctness,
comparatively. Reaching the circle north
or south, it would be much better were the
point fixed upon a ring so that it can be
readily placed at any inclination, so obvia-
ting errors by Irregularities in taking
points and plans.
DIRECTION AND POSITION.
E. W. Hyde read thirty-minRte paper
upon the calculus of direction and posi-
ton, which was replete with solutions of
mathematical problems, but which would
I'LL too much space to warrant the GLOBE
in publishing it, worthy rs it is. It oceu-
pied an hour in reading, although only
intended to consume thirty minutes.
DARK-FIELD ILLUMINATION.
Here followed very interesting five
minute talk by Prof. Rogers upon an i'm
proved method of producing dark-feld
illumination of lines ruled upon glass. He
first spoke of the old method of making
observations of stars upon dark fields, and
explained the errors which had fallen to
many astronomers, and graphically eluci-
dated the fact that afterrepeated and care
full experimental tests he had found that by
letting the light, which is held at an angle
of forty-fve degrees, into the telescope
and then splitting the rays by means of
two opposite mirrors throwing them upon
the horizontal line, an almost perfect light
is secured, and it then becomes quite easy
to discover with positive dist1nctness, stars
of the smaller magnitude upon a dark
field. This result, however, can only be
attained when the light is held at an angle
of fortyfve degrees.
Other professors differed from Prof
Rogers. claiming that the best possible
results could only be obtained through the
use of red light. Prof. Holden was an ad-
vocate of the use of red light upon dark
field observations. He had tried it many
hundred times and found it never failed
him. He was not prepared, however, to
explain the cause, but was satisfied of the
effect. Prof. Rogers agreed that it was
truly an easy matter to discern
stars by the use of red lights, but for
minute observation it is a failure. The
new method, the subject of his address,
being far superior in that respect.
The time having arrived for closing, the
section adjourned without having reached
two papers put upon the programme
those of Prof S. G. Chandler, Jr., upon
the results of tests with the Almacantar
in time and latitude, and one by Prof. j
Eastman on internal contacts in transits
of inferior planets. The time had been
consumed in two long essays which had
been marked twenty and thirty minutes
respectively.