French scientist Étienne-Jules Marey had started by…

French scientist Étienne-Jules Marey had started by studying blood circulation in the human body, then shifted to analyzing heart beats, respiration, muscles (myography), and movement of the body.

To aid his studies, he has developed many instruments for precise measurements.

For example, he was successful in selling an instrument called Sphygmographe to measure the pulse.

In 1869, Marey had constructed a very delicate artificial insect to show how an insect flies and to demonstrate the figure-8 shape it produced during movement of its wings.

He had then become fascinated by movements of air and started to study bigger flying animals, like birds.

Marey studies other animals, too.

He had published La Machine animale in 1873 (translated as "Animal Mechanism").

The English photographer Eadweard Muybridge had carried out his "Photographic Investigation" in Palo Alto, California, to prove that Marey was right when he wrote that a galloping horse for a brief moment had all four hooves off the ground.

Muybridge had published his photos in 1879 and received some public attention.

Intrigued by Muybridge’s photographic motion studies, Marey devises a means of shooting multiple pictures with a single camera in 1882.

Marey's chronophotographic gun is capable of taking 12 consecutive frames a second, and the most interesting fact is that all the frames are recorded on the same picture.

Using these pictures, he studies horses, birds, dogs, sheep, donkeys, elephants, fish, microscopic creatures, molluscs, insects, reptiles, etc.

Some call it Marey’s "animated zoo".

Marey also conducts the famous study about cats landing always on their feet.

He conducts very similar studies with a chicken and a dog and finds that they can do almost the same.