VOL. LXXVIII.] PHILOSOPHICAL TANSACTIONS. 483 



therefore of s for this year will be expressed by the 2 fractions ~-— ^^r" h 



•^ ^ ^ ~ ^ ' Again, the payment of s in the 3d year will depend either on a 

 and b's both dying in that year, and b having died last ; or on b's dying in that 

 year, and a's dying in the 1st or 2d years. The value therefore of s for this year 

 will be = ^'° h~ "'■ — ~ "113 — • ^y proceeding in this manner for 

 the other years the whole value of the reversion will be found = 



4. (i.±f^iiff^l±+ (fltflt-^2jiiz/i + &c. Thefirstoftheseseries,bypro- 

 ceeding in the same manner as in the solution of the 2d problem, may be found = 

 i X (k - ak) - ^^-^ - 4. . (b - ab) + -j: X (c - AC) ; and the 2d 



series may be found = — -7-* X (c — ac) H . Hence the whole value 



- . . .„ , ^^ f9>r . (k — ak) — c . (c - ac) (r - 1 . (b — ab) 



of the reversion will be = s X ( ^ j^ — ^ — -^^ -^ -. 



a. E. D. 



Having now the value of the sum s depending on the older of the 2 lives dying 

 last, the value of the same sum depending on the younger of the 2 lives dying 

 last is easily obtained, by subtracting the value first found from the whole value 

 of the reversion after the extinction of both lives. The answers computed by this 

 rule differ rather more from those computed by Mr. Simpson's approximation than 

 they do in the preceding problem. 



JCXI. Of a Remarkable Transposition of the Flscera. By Matthew Baillie, 



M. D. p. 350. 



Nothing tends more to illustrate the powers and the wisdom of nature than the 

 investigation of the structure of animals. We there find a most wonderful deli- 

 cacy of mechanism, and exquisitely adapted to a variety of purposes. This how- 

 ever is not to be better seen by following nature in her common track than by 

 observing her wanderings. In these she often shows more particularly the extent 

 of her powers, and throws light on her ordinary plans. Such circumstances give 

 importance and value to the observation of singular phenomena. The variety in 

 animal structure, an account of which is presented in this account, is a complete 

 transposition in the human subject, of the thoracic and abdominal viscera, to the 

 opposite side from what is natural. It is so extraordinary as scarcely to have been 

 seen by any of the most celebrated anatomists, and indeed has been but very 

 generally noticed at all. The circumstance has been mentioned, but it has not 

 been particularly described so as to make it thoroughly known, or to establish its 

 certainty. It was hanging in the minds of many as doubtful, whether such a 



3 Q 2 



