97th Auction

2018/5/12

Lot 544

F. Dent, 61 Strand, London, Case No. 1381, 60 mm, circa 1870
A rare meridian instrument 'Dipleidoscope' according to Dent's patent of 1843
Case: brass.
The instrument was developed by E. J. Dent (1790-1853) and his partner J. M. Bloxam and promised to be a simple method to determine true noon. The outer glass panel and the two mirrors behind it create a hollow prism that is aligned in parallel to the axis of the Earth. When the instrument is set up correctly, a double image of the sun is created on the glass panel as well as on the inner mirrors. When the angle of the mirrors coincides with the angle of the sunlight, the two images overlap and it is local true noon. The instrument is said to be capable of determining true noon to within a few seconds.
Our instrument was created by his son and successor Frederick William Dent. It is identical in design to the instrument in the German Museum in Munich and is often illustrated in publications. Even Dent himself uses this model in his paper on theory and use of his invention; it is also explained in the Civil Engineer and Architects' Journal of July 1844.

Sold

estimated
9001.200 €
Price realized
1.000 €