filar micrometer
Datecirca 1894
Inventory Number1997-1-0291
ClassificationMicrometer
Subject
Maker
Alvan Clark and Sons
?
1846 - 1958
User
Bowdoin College, Department of Physics
founded after 1794
Cultural Region
Dimensions18.2 × 9.2 × 7 cm (7 3/16 × 3 5/8 × 2 3/4 in.)
Material
DescriptionThis is an eyepiece micrometer for a telescope that takes eyepieces with 1 1/2 inches outer diameter. It is made of brass wtih silvered scales.
Horizontal motion is controled by a worm screw. Rotational motion around the axis of the telescope is by a screw and geared circle, which is divided 0-360 degrees, every 1 degree. There is no vernier. A micrometer drum has two divided rings, one running 0-100 and the other 0-30.
On the other side of the box from from the drum there is a blackened collar holding a condensing lens. This would be for the introduction of light to illuminate the cross hairs.
Horizontal motion is controled by a worm screw. Rotational motion around the axis of the telescope is by a screw and geared circle, which is divided 0-360 degrees, every 1 degree. There is no vernier. A micrometer drum has two divided rings, one running 0-100 and the other 0-30.
On the other side of the box from from the drum there is a blackened collar holding a condensing lens. This would be for the introduction of light to illuminate the cross hairs.
Signedunsigned
Functionseparations between objects can be measured. One typical astronomical use would be in observing the separation of double stars.
ProvenanceDepartment of Physics, Bowdoin College; gift to CHSI by Professor Elroy O. LaCasce, 1997.
Historical AttributesUsed by the Physics Department of Bowdoin College.
Wm Gaertner & Company
Date: 1900-1920
Accessories: micrometer eyepiece, eyepiece adaptor
Object number: 1997-1-1836
Fauth & Company
Date: circa 1885
Accessories: spare parts, wood case
Object number: 1996-1-0028
Buff & Buff Manufacturing Company
Date: circa 1905
Accessories: wood case; leather case; right-angle prism; plumb bob; oil flask; tripod (5174b)
Object number: 5174a
Dollond & Son
Date: 1758-1764
Accessories: Fitted mahogany box
Object number: 0059
Troughton & Simms
Date: 1868-1870
Object number: 2006-1-0051
Alvan Clark and Sons
Date: 1910
Object number: 2003-1-0077b
Bausch & Lomb Optical Company
Date: circa 1900
Accessories: case
Object number: 1997-1-0804
Troughton & Simms
Date: circa 1875
Accessories: 3 eyepieces; 1 diagonal; 1 set of shades; magnifier; dust cap; case.
Object number: 1996-1-0566
Andrew Yeates
Date: circa 1840
Accessories: case, second eyepiece, plumb bob
Object number: 5235