VOL. LI.] PHILOSOPHICAL TRANSACTIONS. 485 



This horse was 25 years old, had been often ill, and under the farrier's care ; 

 which made Mr. A. desire to have it opened when dead. 



The whole stone, when first taken out, weighed 10-i-lb.: and Mr. A. caused 

 it to be sawed in two, that a better judgment might be made of the manner of 

 its formation. Sev^eral smaller concretions were also found in the colon ; but 

 they were much less solid, and more irregular than the large one. This ball was 

 full 7 inches in diameter, and consisted of many laminae or coats, which formed 

 a number of concentric circles, around a nucleus in the centre, which seemed to 

 be a small shiver of black flint. Fifteen or l6 of these coats were easily distin- 

 guishable, and some had been broken ofi^: they varied something in colour, and 

 were in general so stony that they would probably take a pretty good polish. 

 The coats differed in thickness, according perhaps to the time they were in form- 

 ing: for it should seem, if conjecture might be allowed, that each coat was 

 formed in a longer or shorter time, according to its thickness; and that between 

 the finishing of one coat, and the beginning of the next, there was some interval 

 of time, and some suspension of that attractive power whereby, or of that com- 

 ponent matter whereof, the several coats were respectively formed. 



LXf^IlL An Explanation of the Modes or Tones in the Ancient Grecian Music. 

 By Sir Francis Haskins Eyles Stiles, Bart., F. R. S. p. 6q5. 



This is another ineffectual, though voluminous attempt, after Meibomius and 

 Wallis, to explain and restore the music of the ancients. 



LXIX. An Inquiry into the Measure of the Roman Foot. By Matthew Raper, 



Esq.,F.R.S. ^.774. 



The ancient foot-rules now remaining ; the representations of the foot in 

 sculpture; and the measure of it, derived from the congius, differ so much 

 among themselves, and from each other, as to be insufficient evidences sepa- 

 rately: and the great disagreement of the foot from the congius, with the rest, 

 has not hitherto been satisfactorily accounted for. The foot-rules found in old 

 ruins at Rome are of various lengths; and the age of none of them being cer- 

 tainly known, no precise measure can be determined from them, otherwise than 

 by taking a mean from such as appear to be most perfect. But though this may 

 have been the foot in use at some time or other, yet as these rules are probably 

 of different ages, both the greatest and least of them may have answered to the 

 standards of their times. For though we have no account of any alteration ever 

 made in the standard of the Roman foot, yet the wear of a standard measure by 

 use, and the making new to replace the old ones, must probably create a dif- 

 ference; especially as the Romans had not those inducements to so precise an 

 accuracy in these matters as the later discoveries in natural philosophy (particu- 



