Grace's Guide is the leading source of historical information on industry and manufacturing in Britain. This web publication contains 129,779 pages of information and 204,808 images on early companies, their products and the people who designed and built them.
Engineer, of Leith Walk Foundry, Edinburgh.
1821 The brothers founded a business in Sciennes, Edinburgh (although at his age it must be questioned whether George was involved from the start).
1841 Married Eliza Noble in Edinburgh
1841 George Bertram 30, millwright, lived in East Scinnes, Edinburgh, with Eliza Bertram 20
1851 Engineer (master Employing 50 Men), lived in Edinburgh St Cuthberts, with Eliza Bertram 28, Margaret Bertram 9, Janet Bertram 7, George Bertram 6, Eliza Bertram 4, Jane Bertram 2
1861 Engineer employing 94 Men and 12 Boys, lived at Sciennes Hill House, Edinburgh, with Eliza Bertram 39, Margaret Bertram 19, George Bertram 16, Eliza Bertram 14, Jane Bertram 12, William Bertram 10, David Bertram 8, Andrew Bertram 5, John Bertram 3
1853 Patent on Improvements in the manufacture of paper
1862 Patent on paper making machinery.
1877 Horizontal engine for Craig's Paper Mill, Dalkieth. 
1880 Retired from the business after 34 years running the business of George and William Bertram
1881 George Bertram 73, retired engineer, lived in Newington, Edinburgh with Eliza Bertram 59, Andrew N Bertram 25, John Bertram 23, master engineer, Elizabeth N Bertram 7
1881 Died in Edinburgh
NB In contrast to the reference, it seems unlikely that the Bertram brothers could have spent 20 years in Dartford (as stated there) before setting up business in 1821 so this part of the statement has been removed.