S1 : science has already conferred an immense boon on mankind by the growth of the medicine.

S6 : the general death rate in 1948 (10-8) was the lowest ever recorded up to that date.

P : it has continued ever since and is still continuing.

Q : I the eighteenth country people expected most of the their children to die before they were grown up.

R : in 1920 the infant mortality rate in England and wales was 80 per thousand; in 1948 it was 34 per thousand.

S : improvement began at the start of the nineteenth century, chiefly owing to vaccination.

The proper sequence should be-