VOL. LXXVII.] PHILOSOPHICAL TRANSACTIONS. 297 



originally intended to produce in general more than 2 ; yet, from what we know 

 of the womb and its appendages, and what from the latest experiments we are 

 led to conjecture as to the mode of conception, we cannot presume a priori to 

 set limits to the fertility of nature, nor determine decisively what number of 

 foetuses may be conceived and nourished to a certain period in the human uterus 

 at the same time. 



The present singular and well-attested case assures us, that 5 have certainly 

 been born at once, and we have no title absolutely to reject all the testimonies 

 of even more numerous births, or to say that, in some rare instances, this 

 number has never been exceeded. What has tended to render relations of this 

 sort ridiculous, and to throw a degree of discredit on the whole, is the many 

 marvellous, and evidently absurd and incredible histories, which not only the 

 retailers of prodigies, but even the credulous writers of medical observations, 

 have collected. I need only refer those, who wish to amuse themselves with 

 surprising relations of this kind, to the curious collections of Schenkius, Schu- 

 rigius, Ambrose Parey, and others. 



But, in order to show how very uncommon births of this kind are, and how 

 truly singular the case communicated by Mr. Hull to Dr. Blane is, I take the 

 liberty to subjoin a short view of the usual course of nature in this matter 

 among our own country-women, where we are least likely to be deceived. 

 Though female fertility certainly varies according to the climate, situation, and 

 manner of life ; yet, I believe, it may be taken for a general rule, that where 

 people live in the most simple and natural state, if they are the best nourished, 

 and if they enjoy the firmest health and strength, they will there be the most 

 fertile in healthy children ; but we have no data to determine that they will there 

 have the greatest number at one birth. At the British Lying-in Hospital, 

 where we have had 18,300 delivered, the proportion of twins born has been 

 only 1 in 91 births. " In the Westminster Dispensary, of 1 897 women delivered, 

 the proportion of twins has been once in 80 births ; but in the Dublin Lying-in 

 Hospital, where above 21,000 have been delivered, they have had twins born 

 once every 62d time. The average of which is once in 78 births nearly, in 

 these kingdoms. 



The calculations made in Germany from great numbers, in various situations, 

 state twins as happening in a varied proportion from once every 65 th to once 

 every 70th time. But in a more accurate and later calculation made at Paris, 

 by M. Tenon, Surgeon to the Salpetriere, we learn, that in 104,591 births the 

 proportion of twins was only 1 in 96, which is only a small degree less than we 

 have calculated at the British Lying-in Hospital. It would be easy to add other 

 calculations, all differing from these and from each other, more or less ; but 

 VOL. xvj. Q A 



