ABSTRACT
An early scientific reference on the buoyancy of human body was found in 1750’s (Robertson, 1757). This study was driven by the author’s motivation to answer the question “what quantity of fir or oak timber would be sufficient to help a man afloat in river or seawater (Robertson, 1757, p.33).” The statement clearly indicates that the author believed a motionless human body was not floatable in water. Robertson constructed a cistern and asked ten “labouring men” who were “fortified with a large dram of brandy” to sink in the
water-filled cistern. He then measured the height of the water surface to compute the volume of the subject, so that the buoyant force acting on the subject in water was determined. In the study, the buoyant force (mean: 729 N) was found to be greater than the weight (mean: 649 N) for nine out of 10 subjects, and the author concluded that (a) excepting some, “every man was lighter than his equal bulk of fresh water” and consequently, “many might be preserved from drowning” and (b) “a piece of wood, not larger than an oar, would buoy a man partly above the water.” This finding was supported by a study conducted by Pettigrew (1874). He investigated the floating positions of motionless humans and claimed that everyone could float in water if breathing was held naturally and the body was relaxed.
