Thus, one person could slew the telescope with ease, and a gravity-powered clock drive
acting on the polar axis could compensate for Earth's rotation.
(If you have a clock drive
, turn it off.) That direction is west.
Furthermore, an unpublished study spearheaded by neuroscientist Paul Gamlin of the University of Alabama at Birmingham demonstrates that the eyes' blue-sensitive ganglion cells that relay light signals to the biological clock drive
this pupil constriction in rhesus monkeys--and presumably people.
Around 1650, Robert Hooke adapted this joint to a rotating shaft in a clock drive
. The automobile and internal-combustion engine have been the forces driving contemporary flexible-coupling technology.
However, because his telescope had setting circles and a clock drive
, Schiaparelli could point it to the right place in the sky and study Mercury for hours at a time.
An equatorial mount often comes with a clock drive
. Turn it on, and it slowly rotates the scope to cancel out the Earth's rotation and keep the telescope pointed at a celestial target--a huge convenience.
A clock drive
kept the selected celestial object in the center of the visual field.
Besides, the primary mirror needed to be cleaned, and there was no clock drive
The equatorial mount had a weight-driven clock drive
that was precisely regulated by a spinning flyball governor.
Our home-built clock drive
used surplus gears and various spare parts.
Zhang's manuscript on the water-driven clock drive
, Apparatus for Rotating an Armillary Sphere by Clepsydra Water, is now known only from quotations by later scholars, but they confirm that his armillary was designed to track the Seven Luminaries (Sun, Moon, and the five planets visible to the unaided eye), seasonally significant events, and the times of dawn and dusk, and to verify their proper coordination with the calendar.
I started the clock drive
and camera on the northern one 7 minutes before the graze began, then rushed to the southern scope to record it in person there.