Sitzungsberichte der Königlich Preußischen Akademie der Wissenschaften zu Berlin
This series of journals contains papers by Lindemann and Weierstrass on the Lindemann-Weierstrass Theorem. Scans of the issues from 1882 to 1900 are available in jpeg form on the website of the Berlin-Brandenburgische Akademie der Wissenschaften through this link
Volumes 1 (1869) to 306 (1996) may be accessed through the Göttingen University website here.
Journal für die reine und angewandte Mathematik (Crelle’s Journal)
Volumes 1 (1826) to 493 (1997) may be accessed through the Göttingen University website here.
Lady’s and Gentleman’s Diary
The Lady’s and Gentleman’s Diary (published prior to 1841 as The Ladies’ Diary and Gentleman’s Diary) was a magazine of recreational mathematics, word puzzles and poetry. It may be accessed through this link.
Philosophical Transactions of the Royal Society
Volumes from 1665 to 1886 may be accessed here.
JSTOR (here) allows users access to a limited number of journal articles each fortnight. Registration as a user is free.