Eye of the Beholder . by Laura J Snyder . ( Head of Zeus , £25 ) The behaviour of Dutch natural scientist Antoni van Leeuwenhoek was nothing if not eccentric . In 1677 , at the age of 41 , he embarked on an extraordinarily gruesome experiment , using his body as a guinea pig . Antoni van Leeuwenhoek ( pictured in a portrait ) used his body as a guinea pig in an experiment . He took three lice , nestled them among the hairs of his calf , rolled up a tight stocking so that the insects were bound to his leg and then left the stocking on and did not bathe for six days . On the seventh day , he removed the stocking and counted more than 80 eggs but no young lice . In the interests of empiricism , the stocking went back on for another three days . Finally , the stocking came off to reveal at least 25 lice running up and down his leg . ‘ This spectacle of all the young lice filled me with such aversion to the stocking , ’ he wrote , ‘ that I threw it , along with all the lice in it , out the window. ’ He rubbed down his legs with ice , then took up his pen to calculate the louse ’ s reproduction rate . He estimated that two pairs of lice could generate 10,000 young in only eight weeks . While Leeuwenhoeck was thus engaged , another great Dutchman , Johannes Vermeer , was intent on his own more genteel studies in his house on the opposite side of Delft ’ s market square . Draped in a black cloth , Vermeer spent hours peering into the box-like interior of a camera obscura , an ancestor of the photographic camera . This was a light-tight wooden chamber with a hole or lens on one side , which could be used to project an image of a scene on to a glass plate or wall . They had been used for party tricks and for viewing solar eclipses but were increasingly being employed by artists to render paintings more lifelike than ever . The experiments of these two men are the subject of Laura J. Snyder ’ s new biography . She asks an intriguing question : could Vermeer and Leeuwenhoek , who were born in the same week , lived and worked their entire lives in an area not much larger than a football pitch , and who had friends in common , have exchanged ideas and inspired each other ’ s work ? This is much more than a joint biography . It is a portrait of an age of insatiable intellectual curiosity . The 17th century gave us an inventory of instruments which far extended man ’ s understanding of the world : accurate thermometers and barometers , the air pump , the pendulum clock , improvements to the telescope , the refinement of the microscope . Leeuwenhoek ’ s mastery of lens-grinding saw him build a microscope capable of magnification up to 480 times . Scientists and dilettanti assembled cabinets of curiosity filled with rare animal and shell specimens . Leeuwenhoek ’ s collection included the eye of a whale , pickled in brandy . Anatomical theatres for the dissection of bodies were built in Padua , Bologna , Leiden , Delft and Amsterdam . According to one chronicler , sumptuously dressed ladies would attend dissections of the bodies of executed criminals and then go straight to that night ’ s ball . Snyder moves effortlessly not just between Vermeer ’ s studio and Leeuwenhoek ’ s laboratory , but all over Europe , from the universities of Italy , to the halls of the Royal Society in London , then the world ’ s pre-eminent scientific institution . Leeuwenhoeck wrote about 300 letters to the Royal Society , charting 50 years of experiments . He addressed them as ‘ curious gentlemen dabblers ’ . One of his great discoveries was the observation of thousands of swimming creatures , which he called animaculae or little animals , in murky water . He estimated there could be more than eight million of them in a single drop . Later generations would recognise them as bacteria . He was also the first scientist to observe the existence and movement of sperm . No one had yet seen the human sperm or the egg or understood their part in reproduction . Leeuwenhoek politely wrote to the President of the Royal Society : ‘ What I investigate is only what , without sinfully defiling myself , remains as a residue of conjugal coitus. ’ One feels a certain amount of sympathy for his wife , Cornelia . What with the lice and the post-conjugal microscope experiments , she must have been a very patient woman . The great pleasure of this book is how Snyder makes the science clear to the layman . I have a degree in history of art and only one measly science GCSE in biology . Yet I was left more eager to peer down the lens at one of Leeuwenhoek ’ s slides , than to stand before even the most pellucid of Vermeer ’ s exquisite paintings .
At 41 van Leeuwenhoek used his body as a guinea pig in an experiment . Vermeer spent hours peering into the box-like interior of a camera obscura . He was able to see that light travels through glass, but not through water or air.