ON INSTRUMENTS FROM ITAL Y. 103 



a noble Venetian, who, writing to Galileo on the 9th of May, 1613, 

 says : " The instrument you invented for measuring heat, has been 

 reduced by me into several very convenient and excellent shapes, so 

 much so, that the difference of the temperature from one room to 

 another can be seen up to 100 degrees. By the help of it I have 

 observed several marvellous things, for example, that in winter, the 

 air is colder than ice and snow ; that at this season water appears 

 colder than the air ; that very little water is colder than a great 

 quantity, etc.," adding that some peripatetics believe, " that the con- 

 trary effect ought to ensue, because heat having, as they say, an 

 attractive power, the vessel in becoming warm ought to draw the 

 water to itself. Then Vincenzo Viviani, in his life of Galileo, affirms 

 that between 1593 and 1597 he invented the thermometer. Galileo's 

 not having made any mention of his works ought not to create 

 surprise ; for the fact is that he undoubtedly communicated all his 

 discoveries to his friends and disciples long before he made up his 

 mind to write about them. 



But in any case it is well known that the thermometer was for a long 

 time called the Florentine Instrument ; and this indeed is accounted 

 for, since it was in Florence that it received its most important im- 

 provements, thanks especially to Ferdinand II. Sagredo, however, 

 was the first to divide it into degrees (in 1612), and it was he also that 

 closed it hermetically about the year 1615. The improvements effected 

 by Ferdinand were described by Padre Urbano Daviso, who, after 

 having mentioned that he gave it a special shape (corresponding to 

 the one we now see), and that he filled it with coloured spirits of 

 Avine instead of with water, which, by freezing, breaks the glass, adds : 

 *' Hence it may be seen which of two liquids gives out the more or less 

 heat or cold ; and it will be possible to warm water, or a room, or a 

 furnace to any degree ; to keep it at that temperature, or raise it ; to 

 know when a thing has reached that state of heat necessary for cooking 

 it properly ; all operations from which it may be said that the chemical 

 art has received its finishing touch ; and in the same way it will be 

 possible, with instruments made on the same principle, to find out the 

 heat and coldness of any province, due observations having been taken 

 beforehand, c. And by this means it has been discovered that 

 spring-water and also caves, cellars, grottoes, and other deep subter- 



