Since the Earth rotates at a fairly constant speed, the time when certain stars were seen through the transit telescope was known. The Earth's motion served as the final reference and it was used to regulate the clock. Makes distance measurements at sea or on land. A dial is rotated until two images seen through a split lens come together. Distance is calculated according to the reading on the dial.
Measures distances on land.
Used to measure and do calculations. Sectors were made with scales suited to different trades. Scales are based on lengths and angles, as well as logarithmic and trigonometric functions. For more information on our scientific instruments, contact the Curator, Physical Sciences and Space, R.C. Brooks .