13
objects only three to nine times their true size. However, news about
this important tool for looking at very small things quickly spread
across Europe.
In the following decades the microscope underwent a series of
slight improvements. Robert Hooke, a self-educated English scien-
tist with a brilliant mind and a prickly personality, tinkered with the
height and angle of microscopes to achieve magnifications of fifty
times actual size. He also adjusted light sources for better illumina-
tion. Using his improved microscope, Hooke made a historic dis-
covery. Peering at a thin slice of cork, he noted that the magnified
substance looked like a honeycomb pattern of empty pores or boxes
enclosed by a surrounding wall. He referred to these boxes as cells,
since they reminded him of the small rooms in a monastery. (The
word
cell
is short for the Latin
cellula
, meaning a small compartment.)
Hooke observed similar arrangements in wood and other plants. In
1665 Hooke published
Micrographia
, in which he described his mag-
nified observations of everything from flint to fabric to frozen urine.
He also included detailed drawings of what he had seen.Hooke touted
the microscope as a tool “only to promote the use of mechanical helps
for the Senses, both in the surveying the already visible World, and
for the discovery of many others hitherto unknown.”
3
Micrographia
became the equivalent of a best seller, with learned readers marveling
at the miniature world it revealed.
An Unlikely Scientist Looks at Cells
Hooke’s illustrated book inspired a Dutch tradesman named Anton
van Leeuwenhoek to pursue his own research. Leeuwenhoek began
to grind lenses and make microscopes as a pastime. The single-lens
instruments he made were simpler in design than the Jansens’ and
Hooke’s compound microscopes and less like microscopes used to-
day. Nonetheless Leeuwenhoek ground each lens with great skill and
was ingenious in his use of lighting. The microscopes he built could
achieve magnifications of 200 times or more in clear, bright images.
Leeuwenhoek also possessed remarkable eyesight, boundless curios-
ity, and a passion for detail. “For his studies,” writes the art historian
Jonathan Lopez, “he interposed the specimen between lens and light
source, much as children of later generations would do when holding
