This is going around the math-sci listservs:

The Royal Society has digitized & onlined all of its publications (1665-present). Access is free until December:

This is an unbelievable sci/tech resource — 60,000 articles by folks from Newton and Leibniz to Hawking and Chandrasekhar.

Annoyingly, they’ll start charging for access after December. Grab the good parts while it’s still free.