102 SECTION PHYSICS. 



already presented his compass to the Prince of Holstein, and shortly 

 afterwards he sent two others in silver, the one to the Archduke 

 Ferdinand of Austria, the other to the Landgrave of Hesse ; and he 

 mentions besides that he had had 100 made in Padua by Antonio 

 Mazzoleni, which he distributed among his patrons and admirers. 



Here is the thermometer, or rather the thermoscope, as it first 

 appeared from the hands of Galileo. 



As far as my knowledge goes, the invention of the thermometer has 

 been attributed to several philosophers ; among the principal are 

 Bacon, Robert Fludd, Cornelis van Drebbel, and Sanctorio. 



In the first work of Bacon, " De Augmentis Scientiarum," the ther- 

 mometer is not mentioned, nor is there any allusion to it in his second 

 work, " De Sapientia Veterum ;" but in the " Novum Organum," 

 published in 1620, he describes a thermometer similar to the one you 

 see before you without, however, declaring himself its inventor. With 

 regard to Fludd, he published a description of a thermometer about 

 the year 1603, after having visited Italy and spent some time at 

 Paclua. Sanctorio, without giving himself out as the inventor, 

 describes a thermometer in his works published in 1625. In favour 

 of Galileo, however, we have the testimony of Padre Benedetto 

 Castelli, who in a letter written in 1638 to Dr. Ferdinando Cesarini, 

 relates as follows : " I now call to mind an experiment shown me, more 

 than thirty-five years ago, by Signer Galileo. It was this : a little 

 glass bottle was taken of about the size of an egg, having a neck thin 

 as a stalk of corn and about two spans long, and it was well warmed 

 with the hands [you see that the instrument I am holding corresponds 

 perfectly with this description, so that I am able to repeat the experi- 

 ment before you] ; then, the mouth of the bottle being turned upside 

 down into a vessel placed underneath, in which was a little water, 

 and the warmth of the hands being removed, the water immediately 

 began to rise in the neck, and continued to do so until it was more 

 than a span higher than the level of the water in the vessel. Signor 

 Galileo had made use of this effect to construct an instrument for 

 investigating the degrees of heat and cold/' 



With regard to this instrument we might well say that Galileo 

 would thus have invented the thermometer even before the year 1603. 

 We have, moreover, the evidence of Signor Giov. Francesco Sagredo, 



