73 SI 
Missouri Botanical Garden 
George Engelmann Papers 
INTRODUCTORY. 
H AYING opened our new manufactory with greatly increased 
facilities, we will continue to construct the very best instruments 
for fixed observatories, field astronomy, geodetic and all kinds of 
engineering work. 
Adjoining the factory, we have erected an observatory with a com¬ 
plete outfit of instruments, where customers can examine and test our 
instruments before purchasing. 
A good assortment of instruments, excepting those of very large 
size, are always on hand. Our warrantee is not limited as to 
time, and all reasonable demands on the part of owners of instru¬ 
ments of our manufacture will be promptly complied with. 
The optical parts of our instruments are in strict accordance with 
the uses for which they are intended. By the judicious use of lenses 
of large aperture, we gain light and brilliancy of image without destroy¬ 
ing the flatness of field, or decreasing the magnifying power. It is need¬ 
less to say that the objectives are perfectly achromatic, and the eye¬ 
pieces in strict accordance with the purposes the instruments are used 
for. All field instruments have achromatic eye-pieces ground after 
Kellner’s and Steinheil’s formulas. 
The graduations are always on solid silver, unless otherwise 
mentioned, and we draw especial attention to the correctness and 
beauty of our divisions. The graduating and centring is done by us 
personally, and no instrument is allowed to go with any perceptible 
error. 
The next edition of our catalogue will contain a full description, 
with illustrations, of our new Dividing Engine, which is rapidly ap¬ 
proaching completion, by which readers will become familiar with the 
means used to arrive at the astonishing perfection. 
Our Level-bubbles are all carefully ground, and their sensi¬ 
bility is in accordance with the use of the instrument they are intended 
for. Those for astronomical work, or for the higher class of engineer¬ 
ing instruments, are filled with ether and provided with air-chambers 
to regulate the length of bubble in changes of temperature. Those 
for instruments intended to indicate minutes of arc are also carefully 
ground, but are filled with pure alcohol. The excellence of our Levels 
