Friday, March 04, 2011

I can see clearly now

Here’s a little piece I wrote for Nature news. To truly appreciate this stuff you need to take a look at the slideshow. There will be a great deal more on early microscopy in my next book, probably called Curiosity and scheduled for next year.

The first microscopes were a lot better than they are given credit for. That’s the claim of microscopist Brian Ford, based at Cambridge University and a specialist in the history and development of these instruments.

Ford says it is often suggested that the microscopes used by the earliest pioneers in the seventeenth century, such as Robert Hooke and Antony van Leeuwenhoek, gave only very blurred images of structures such as cells and micro-organisms. Hooke was the first to record cells, seen in thin slices of cork, while Leeuwenhoek described tiny ‘animalcules’, invisible to the naked eye, in rain water in 1676.

The implication is that these breakthroughs in microscopic biology involved more than a little guesswork and invention. But Ford has looked again at the capabilities of some of Leeuwenhoek’s microscopes, and says ‘the results were breathtaking’. ‘The images were comparable with those you would obtain from a modern light microscope’, he adds in an account of his experiments in Microscopy and Analysis [1].

“It's a very trustworthy and interesting article”, says Catherine Wilson, a historian of microscopy at the University of Aberdeen on Scotland. “Ford is the world’s leading expert on the topic and what he has to say here makes a good deal of sense”, she adds.

The poor impression of the seventeenth-century instruments, says Ford, is due to bad technique in modern reconstructions. In contrast to the hazy images shown in some museums and television documentaries, careful attention to such factors as lighting can produce micrographs of startling clarity using original microscopes or modern replicas.

Ford was able to make some of these improvements when he was granted access to one of Leeuwenhoek’s original microscopes owned by the Utrecht University Museum in the Netherlands. Leeuwenhoek made his own instruments, which had only a single lens made from a tiny bead of glass mounted in a metal frame. These simple microscopes were harder to make and to use than the more familiar two-lens compound microscope, but offered greater resolution.

Hooke popularized microscopy in his 1665 masterpiece Micrographia, which included stunning engravings of fleas, mites and the compound eyes of flies. The diarist Samuel Pepys judged it ‘the most ingenious book that I ever read in my life’. Ford’s findings show that Hooke was not, as some have imagined, embellishing his drawings from imagination, but should genuinely have been able to see such things as the tiny hairs on the flea’s legs.

Even Hooke was temporarily foxed, however, when he was given the duty of reproducing the results described by Leeuwenhoek, a linen merchant of Delft, in a letter to the Royal Society. It took him over a year before he could see these animalcules, whereupon he wrote that ‘I was very much surprised at this so wonderful a spectacle, having never seen any living creature comparable to these for smallness.’

‘The abilities of those pioneer microscopists were so much greater than has been recognized’ says Ford. He attributes this misconception to the fact that ‘no longer is microscopy properly taught.’

1. Ford, B. J. Microsc. Anal. March 2011 (in press).

1 comment:

Unknown said...

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compound microscopes