It is usually a double-image micrometer used to measure the diameter of the image of the object glass.
From the en.wikipedia.org
The first application of the divided object-glass and the employment of double images in astronomical measures is due to Servington Savary from Exeter in 1743.
From the en.wikipedia.org
John Dollond, in 1754, combined Savary's idea of the divided object-glass with Bouguer's method of measurement, resulting in the construction of the first really practical heliometers.
From the en.wikipedia.org
Sagging will only occur relatively early in the lifetime of a glass object.
From the newscientist.com
The object was a glass bottle containing a flammable liquid, Berger said.
From the washingtonpost.com
An object printed from powdered glass, using the Solheim Lab's new Vitraglyphic process.
From the sciencedaily.com
Venetian glass is a type of glass object made in Venice, Italy, primarily on the island of Murano.
From the en.wikipedia.org
As Jerry tried to leave at 4 a.m., he turned into a glass object that John was swinging around the room.
From the tennessean.com
The woman told investigators she likely would have been hit by the object if the glass had not stopped it.