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DK Eyewitness - Astronomy

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Napier’s bones<br />

One of the problems that has always<br />

faced astronomers is the seemingly<br />

endless calculation that is needed to<br />

pinpoint the true positions of the stars<br />

and the planets. In 1614 John Napier<br />

(1550–1617), Laird of Merchiston in<br />

Scotland, published the first full set of<br />

logarithmic tables. In 1617 he invented a<br />

series of rods engraved with numbers in<br />

such a way that they could be set side<br />

by side and used for doing complex<br />

multiplications and divisions. The rods,<br />

usually made of ivory or bone, were<br />

soon known as “Napier’s bones.”<br />

Rods marked with<br />

Napier’s numbers<br />

Number display<br />

Family loyalty<br />

Caroline Herschel (1750–1848)<br />

was astronomical assistant and<br />

housekeeper to her brother, the<br />

great observational astronomer<br />

Sir William Herschel (p.54).<br />

While he was busy grinding<br />

mirrors—a delicate task that<br />

could take up to 16 hours—<br />

Caroline would spoon-feed<br />

him as he worked to keep up<br />

his strength. As an astronomer<br />

of note in her own right, she<br />

discovered eight comets and<br />

was an influence on her brilliant<br />

nephew John (1792–1871), who<br />

became famous for his survey of<br />

the southern hemisphere.<br />

Handle<br />

Turning pegs<br />

Astronomical calculator<br />

In the 19th century, instrument makers began to construct mechanical<br />

calculators for complex, often repetitive, mathematical functions.<br />

With one turn of the handle, this calculator can produce<br />

a figure with up to 42 places.<br />

Lantern<br />

Arm rest<br />

Barometer<br />

The astronomical chair<br />

The astronomical chair is quite a late<br />

invention. When astronomers worked with<br />

big mural quadrants (p.25), they needed a pair of steps<br />

to run up and down in order to reach the eyepiece of<br />

the telescope. It was not until the invention of the<br />

transit instrument in the late 17th century that<br />

astronomers could lie back and look at the<br />

stars. Chairs with padding on them<br />

did not appear for another 50 years.<br />

Adjustable<br />

back<br />

Keeping warm<br />

Being an astronomer was not a<br />

glamorous life. Before the advent<br />

of the camera, the job involved<br />

spending long hours in a roofless<br />

observatory, peering through an<br />

eyepiece at the stars, and making<br />

copious notes of observations.<br />

Suitable warm clothing would<br />

have been essential.<br />

Seat<br />

Ratchet for altering<br />

height of seat<br />

Ratchet pin<br />

Wheeled<br />

base<br />

29

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