Description
In November 1944, R.S. Whipple’s donation to the University of Cambridge was put on show in the East Rooms of the Old Schools. The University accepted the donation on the condition that they found a new institution within which to house the collection.

Whipple himself wrote a guidebook to this exhibition, describing some of the more important objects and books on show. The front cover includes the following declaration: “The Exhibits are drawn from the Collection which Mr R.S. Whipple is presenting to the University and will form a nucleus for a History of Science Museum and Library in Cambridge.”

Whipple's own explanatory text for this object was:

"Dipleidoscope. The Dipleidoscope is a simple form of transit instrument designed by J.M. Bloxam about 1875. Several different models were made by E.D. Dent and Co. and the instrument is generally referred to as the Dent Dipleidoscope."
17/10/2025
Created by: Hannah Price on 17/10/2025

Description
This instrument is used to determine true noon to an accuracy of within 10 seconds. A prism creates a double image of the sun, which merge together as the sun approaches its high point in the sky. When the two images overlap, it is local true noon.

The chronometer and clockmaker Edward John Dent patented his design for the dipleidoscope in 1843, and he exhibited the instrument at the Great Exhibition in London in 1851.

Knowing local noon is useful, for example, for checking and correcting clocks. It is also used in the determination of longitude, which can be calculated by finding the difference in time between local noon and midday at the prime meridian in Greenwich. Whilst the former can be found using a dipleidoscope or sextant, the latter must be read from an accurate chronometer set to Greenwich time.
16/07/2015
Created by: Joshua Nall on 16/07/2015