Estimated Draper Numbers and Dating

Since there were no records found for Edmond Draper we have put this information together based on observed instruments using design data and patent information.  We have also put together a list of instruments to help in dating these instruments.   Based on early designs Edmond Draper did not use serial numbers on his instruments and we have determined that Draper used no serial numbers from 1832 to approximately 1859. 

The dating equation is based on only two observed points so there may be some discrepancies. 

An observed transit with no serial number and made with Draper shifting head. Since Draper made his first instrument with shifting head after 1858 this suggests that numbering started after this date

The highest observed serial number is 626 and this instrument must have been made before Draper’s death in 1882.

Also the assumptions that:

            The numbering started at zero

            The number of instruments produced per year is constant

So we are assuming Inst # 0 was made in 1860 and # 600 in 1880 when Draper produced an average of 30 instruments a year.   The average number of instruments produced is confirmed by the Decennial Census of Industry in 1860 & 1870 reports.

The calculated value of 30 instruments per year is reasonable since Young & Heller & Brightly at the same time, with a larger shops, were producing 100 instruments per year.

The formula we are using:   Year = 1860 + num/30

Sample:

Serial Number 423 made in 1874

How to calculate:  423/30=14.1 + 1860 = 1874


In view of the limited data the equation must be used with caution and errors of plus or minus 5 years and possibly larger are to be expected.


Observed Instruments
 
****If you have any Edmond Draper instruments please let us know some details about the instrument so we can refine our details.****