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"The original Merz micrometer of the Cape Observatory, made on Fraunhofer's model. S is the head of the micrometer screw proper, s that of the screw moving the slide to which the so-called "fixed web" is attached, s' that of a screw which moves the eye-piece E. C is the clamp and M the slow motion in position angle, L, L are tubes attached to a larger tube N; the latter fits loosely on a strong hollow cylinder which terminates in the screw V. By this screw the whole apparatus is attached to the telescope." —The Encyclopedia Britannica, 1903

Micrometer

"The original Merz micrometer of the Cape Observatory, made on Fraunhofer's model. S is the head of…

"The observatory. This view is from the field, looking north. On the left is seen the winding Schuylkill, and the rolling country beyond; and on the right, the distant hills of Montgomery county."—Lossing, 1851

Observatory

"The observatory. This view is from the field, looking north. On the left is seen the winding Schuylkill,…

"Observatory at Delhi."

Ancient Indian observatory

"Observatory at Delhi."

Her Majesty's Royal Palace and Fortress, more commonly known as the Tower of London (and historically as The Tower), is a historic monument in central London, England, on the north bank of the River Thames. The Tower of London is often identified with the White Tower, the original stark square fortress built by William the Conqueror in 1078. However, the tower as a whole is a complex of several buildings set within two concentric rings of defensive walls and a moat. The tower's primary function was a fortress, a royal palace, and a prison (particularly for high status and royal prisoners).

Procession to the Tower of London

Her Majesty's Royal Palace and Fortress, more commonly known as the Tower of London (and historically…

The name Traitors' Gate has been used since the early seventeenth century, prisoners were brought by barge along the Thames, passing under London Bridge, where the heads of recently executed prisoners were displayed on pikes. Anne Boleyn, Sir Thomas More, Queen Catherine Howard, and Anne Boleyn's daughter, Elizabeth I, all entered the Tower by Traitors' Gate.

Traitor's Gate, Tower of London

The name Traitors' Gate has been used since the early seventeenth century, prisoners were brought by…

The observatory located at Vassar College, in New York.

Vassar Observatory

The observatory located at Vassar College, in New York.

David Rittenhouse erected a temporary observatory for the purpose of observing the transit of Venus on the Walnut Street front of the State house in Philadelphia.

Walnut Street Front

David Rittenhouse erected a temporary observatory for the purpose of observing the transit of Venus…