STUDIO, APPARATUS, AND METHOD OF 

 WORKING. 



For a proper appreciation of tlie care taken in the 

 Investigation of Animal Locomotion at the University 

 of Pennsylvania to ensure accurate record of the con- 

 secutive phases of the various movements, attention to 

 the system adopted is necessary. 



In the diagram, B is the Lateral background; con- 

 sisting of a shed 37 metres or about 120 feet, long, 

 the front of which is open, and divided by vertical and 

 horizontal threads into spaces 5 centimetres, or about 2 

 inches, square, and by broader threads into larger 

 spaces 50 centimetres, or about 19f inches, square. 



At C and C, 37 metres, or about 120 feet, apart 

 are ''fixed^^ backgrounds, with vertical threads 5 cen- 

 timetres, or about two inches, from their centres, with 

 broader threads 30 centimetres, or about 12 inches, 

 from their centres. 



For some investigations, readily distinguishable in 

 the plates, ^'portaUe^^ backgrounds are used, consist- 

 ing of frames 3 metres wide by 4 metres high, — about 

 10 feet by 13 feet 4 inches, — over some of which black 

 cloth and over others white cloth is stretched, all being 

 divided by vertical and horizontal lines into square 

 spaces of the same description as those of the lateral 

 background. 



These portable backgrounds are used when photo- 

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