436 



ANIMAL MECHANICS. 



appearance of the bundles of common fibres is well compared 

 by Dr. Sibson to 

 the overlapping 

 capes of a coach- 

 man's great coat 

 when twisted. As 

 each layer proceeds 

 from right to left, 

 it twists upon itself 

 and at length dips 

 underneath the 

 layers to which it 

 was superficial at 

 the beginning of 

 its course. 



The following 

 observations and 

 measurements were 

 made on the heart 

 of the ox, several 

 preparations of 

 which were placed 

 at my disposal by 

 Dr. Sibson, and se- 

 veral others made 

 by myself were ex- 

 amined while fresh 

 after long continued 

 boiling. On tracing 

 the course of the 

 superficial common 

 fibres, it is found that 

 they describe a complete circumference in a spiral line previous 

 to entering deeper into the heart in the neighbourhood of the 



