Monday, 22 March 2010

Techniques of seeing - Rickett's 20x Bausch & Lomb

John Steinbeck famously described his great friend and marine biologist Ed Ricketts as follows.

“…There was invariably pinned to his shirt pocket a twenty-power Bausch and Lomb magnifying glass on a little roller chain. He used the glass constantly. It was a very close part of him-one of his techniques of seeing.”

John Steinbeck, The Log From the Sea of Cortez (London: Pan Books, 1960): p57.

I have been trying to work out what type of Bausch and Lomb Ricketts would have used. There are two types still available from the Bausch and Lomb company;

Coddington Magnifiers. These are very specially shaped lenses with a deep central groove usually painted back. The groove acts as a diagphram to limit the distortions found in the almost hemi-sperical lenses. They are quite tricky to use, but because they are ground from single pieces of glass are waterproof.

The figure comes from An Introduction to Applied Optics. L.C. Martin 1932.

Hasting Triplets. As the name suggests they are made by bonding three lenses together. They were invented by C.S. Hastings (1879). On triple objectives with complete color correction. Am. Jnl. Sci.18 429.

H. Coddington, A treatise on the reflexion and refraction of light. Simkin and Marshall, London, 1829.