THE ESSAYS OF JEAN REY. 247 



and we find numerous fragments of earthenware pipes of various 

 forms, but most of the specimens of this sort are merely frag- 

 ments. A few entire pipes of the same mixture of clay and 

 pounded stone which we have in the jars are in existence. One 

 of these is shown in Fig. 13, Earthenware pipes of the same 

 general form as that seen in Fig. 8 have also been found, and 

 very likely this was the more common shape. The pipe repre- 

 sented in the figure is unusually thick and heavy, and apparently 

 was made for service rather than ornament. It is three inches 

 long, and the diameter at one end is an inch and a half, at the 

 other about an inch. The bore is rapidly contracted, so that it 

 soon becomes quite small. Most of the earthenware pipes of 

 this region are very smooth on the outside, having received a 

 finishing coat of fine clay, but this is without it, though the 

 surface is tolerably smooth. 



> 



THE ESSAYS OF JEAN REY. 



By mm. L. a. hallo PEAU and ALB. POISSON. 



AMONGr the men of science of the first half of the seventeenth 

 - century the name of Jean Rey, doctor, of Pdrigord, was 

 long forgotten and is still little known. He was born toward the 

 end of the sixteenth century, at Bugues la Dordogne. Hardly 

 anything is known of his life. He was a doctor of medicine, and 

 devoted himself for several years to researches in chemistry and 

 physics, in co-operation with his elder brother, also named Jean 

 Rey, Sieur de la Perotasse, proprietor of the iron forge at Roche- 

 beaucourt, la Dordogne. He died in 1645, and his days may have 

 been cut short by grief over a disastrous lawsuit. 



Jean Rey invented a water thermometer, or thermoscope, and 

 a wind arquebus, and he even thought of applying his thermome- 

 ter to the uses of medicine. It was certainly one of the first in- 

 struments invented to measure differences of temperature. In 

 his description of it he said : " It is nothing but a little round 

 vial with a long, uncorked neck. In using it, I place it in the 

 sun or in the hands of a fever patient, after having filled it, all 

 except the neck, with water. The heat, dilating the water, causes 

 it to rise more or less, according as the heat is great or little." 



He wrote one little book of a hundred pages, dedicated to the 

 Count de la Tour d'Auvergne, which was printed in 1630, under 

 the title of Essais de Jean Rey, Doctor of Medicine, on an investi- 

 gation of the cause of the increase in weight of tin and lead when 

 they are calcined. This work was not understood by the learned 

 men of that period. It was probably not very widely published. 



