Below are several tables to use in figuring out the approximate age of a Heller & Brightly instrument.

SEVERAL NOTES:

• If a serial number is between 4400 and 6213 use Table I.  These are estimated numbers and are not expected to be in error by more than two or three years.

• If serial number is in range 6313 to 8287 consult Table II.  These are dates the serial numbers were authorized and in some cases the instruments were not finished for several years.

• If serial number is in range 6292 to 6670 consult Table III.  These were instruments that were made in the years 1891 to 1897 and duplicated earlier numbers in an effort to hide production from Charles Brightly.  If the number is listed in the table and the instrument is a transit or level as indicated in the second column, then the third column gives the year the number was authorized, otherwise the year is given in Table II.

• For many of the instruments with serial numbers above 6000, the factory records gives the name of the maker, an approximate date of sale, and the name of the purchaser.

• If serial number is 10,000 or above consult Table IV.  Many of these instruments were never finished.