35>o Dr, Garthshore’s Remarks on 
fhort view of -the ufual courfe of nature in this matter among 
ouf own country- women, where we are lead likely to be 
deceived. 
Though female fertility certainly varies according to the 
climate, fituation, and manner of life ; yet, 1 believe, it may 
be taken for a general rule, that where people live in the moil 
fimple and natural (fate, if they are the beft nourifhed, and if 
they enjoy the firmeli health and ftrength, they will there be 
the mod fertile in healthy children; but we have no data to 
determine that they will there have the greatefl number at une 
birth. 
At the Britifh Lying-in Hofpital, where we have had 
18,300 delivered, the proportion of twins born has been only 
one in 91 births. In the Weftminfter Difpenfary, of 1897 
women delivered, the proportion of twins has been once in 
80 births; but in the Dublin Lying-in Hofpital, where above 
21,000 have been delivered, they have had twins born once 
every lixty-fecond time. The average of which is once in 78 
births nearly, in thefe kingdoms. 
The calculations made in Germany from great numbers, in 
various fituations, Bate twins as happening in a varied propor- 
tion from once every fixty-fifth to once every feveutieth 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 one in 
96, which is only a fmall degree lefs than we have calculated 
at the Britifh Lying-in Hofpital. 
It would be eafy to add other calculations, all differing from 
thefe and from one another, more or lefs ; but I hope thefe are 
fufficient to fhew that nature obferves no certain rule in this 
matter ; 
