STANDARD - Survey Instrument Antique Center!

172
The Berger Solar Attachment
Attachable to Transits, Sizes 1, 5'/2, 2, 4 '/a and 4, having a Full Vertical Circle.
For U. S. Deputy Surveyors, Surveyors and Mining Engineers.
This Solar Attachment may be used as a first-class solar in surface surveying for
determining meridian. The solar telescope being longer and more powerful than
heretofore, and as its horizontal axis is provided with our patented lateral adjustment
* (see cuts a, a on right-hand side of illustration), we are enabled to place its
line of collimation so truly above that of the main telescope as to be exactly in the
same vertical plane.
As a solar attachment, or meridian finder, it is in principle like Pearsons' and that
formerly made by us (see cut page 65), not requiring computation; but instead of the
lens bar, or small telescope, f it is now constructed with a telescope of one-inch aperture
and six-inch focal length, provided with a diagonal eye-piece, colored glass and wires
arranged in a square, as shown on next page and described on page 71.
This solar attachment fastens by means of a screw to the cross axis of the transit
telescope. It has no declination arc. The declination of the sun and the co-latitude
of the place of observation are both set off by the vertical circle of the transit. All
settings for position, viz. that of the polar axis, to be truly at right angles to line of
sight of main telescope and the setting of the declination, are secured by the spirit
level attached to the solar telescope. The degree of precision and simplicity of manipulation
attained thereby is commensurate with that of our Engineers' Transit.
To determine true meridian at any hour of the day it is only necessary that the
declination and refraction of the sun on that particular day and hour be known to the
observer, and that the polar axis be raised precisely to the co-latitude of the place of
observation. The adjustments are few and simple, and need to be verified only from
time to time; besides, they can be readily verified, being similar to those in the transit
proper.
Latitude and transit observations can also be made with this telescope when the
sun's altitude is too high for observations with the mam telescope, in the same manner
as described on page 97 for our Interchangeable Auxiliary Telescope style 1.
This solar attachment can be readily attached or detached from the transit without
altering its adjustments. When detached the transit is then simply an ordinary
complete Engineers' and Surveyors' Transit.
By the use of our Latitude Level t (fastening to the cross axis at the side of the
vertical circle, see cut) not requiring a reading of the vertical circle for every setting
of the polar axis for latitude except once in a day, observations can be made repeatedly
with speed and accuracy. Indeed, with the declination and refraction of the sun previously
worked out for the various hours of the day, observations can be made nearly
as fast as a needle of the surveyor's compass can be read. A concise description and
use of both attachments will be found in the Manual.
The weight of the solar attachment and top telescope combined is 1 lb., with counterpoise,
2 Ibs. that of the latitude level about ; }4 lb. Both are screwed into the in-
:ode Words strument box.
Manthus Price of Solar Attachment with Small Telescope, as
generally supplied for solar work, without counterpoise,! but
with prism and colored glass, $52.OO
Hcentra Price of Latitude Level, as in cut, $15.OO
* Other telescopic solars of similar design as heretofore made may be out from y% to }" from the
center of the main telescope, and then of course there must be a divergence of the lines of sight of
both telescopes involving errors to that amount.
fThe honor of first conceiving the idea of applying a small telescope in place of the lens bar and
of using a spirit level for the accurate setting of the polar axis, belongs to Mr. C. L. Berger, of this
firm. See Catalogue of 1878.
JThis latitude level can also be used for grades and distance measurements, etc. It will be found
to form a very useful adjunct to the Engineers' Transit, even without the solar attachment.
It is not strictly necessary to counterpoise the smaller solar attachment in order to obtain good
work.