146 Sylvius and his Pupils. [lect. 



and water, with food and drink, with sleeping and waking and 

 other like topics. Each aphorism is a deduction from facts 

 determined by most careful measurements of the weight of 

 his body at different times, of his food and of his excretions. 

 But he gives no account whatever of his experiments; in 

 striking contrast to many a modern memoir which seems in 

 great measure hardly more than a transcript of laboratory 

 notes, or at least consists in large part of detailed ' protocols ' 

 of experiments, Sanctorius' work gives only the bare con- 

 clusions. He merely describes in a very general way the 

 method by which he arrived at his results. He had constructed 

 a chair suspended to a steelyard, so that he could, using this 

 as a balance, accurately determine his body-weight, at various 

 times and under various conditions; and his book contains a 

 quaint picture illustrating how he weighed himself before and 

 after a meal. By this means he was able accurately to measure 

 the loss of weight to his body by insensible perspiration. Afl 

 he says in his Preface, " It is a new and unheard of thing in 

 " Medicine that anyone should be able to arrive at an exact 

 "measurement of insensible perspiration. Nor has anyone 

 "either Philosopher or Physician dared to attack this part of 

 "medical inquiry. I am indeed the first to make the trial, 

 "and unless I am mistaken I have by reasoning and by the 

 "experience of thirty years brought this branch of science to 

 "perfection, which I judged more advisable than to describe all 

 " the details of my inquiry." 



In his aphorisms he occasionally gives us glimpses of his 

 experimental results, as when he says, " If the food and drink in 

 " one day amount to eight pounds, the insensible transpiration 

 " will generally amount to about five pounds " ; but as I have 

 said the book consists in the main of deductions concerning 

 changes taking place in the body as the result of this or that 

 condition, the nature of the changes being inferred from data 

 furnished by the amount of the insensible perspiration in 

 relation to the weight of the food and drink, of the sensible 

 evacuations and of the body. Sanctorius thus stands out as 

 the forerunner in the early years of the seventeenth century of 

 that statical method of physiological inquiry which during the 



