Long before anybody dreamed of a shiny iPad or glistening ultrabook, engineers and scientists used to get down to business with mechanical calculators to compute their solutions. While the concept of a mechanical calculator sounds ludicrously simple these days, a peek inside one reveals that they're anything but.

This image, taken by San Francisco-based photographer Kevin Twome, shows a German-built Hamann 505 mechanical calculator from the 1960s. In its day, it sold for sold for upwards of $1,000—that's over $7,000 at today's rates. OK, so there's a limited amount you can actually get done with such a device, but the craftsmanship, engineering and sheer complexity of the 505 is astounding. [Kevin Twone via Dvice]