942 SEC. 18. BIOLOGY. 



" descended to 13^ degrees, although on some occasions the cold air at 

 " Florence reduced it to 7. And when exposed to the rays of the sun at 

 " midsummer, in the open air, and free from any kind of reflection, it rose 

 " to 43, and at the same season, in the shade, to 34." So that the differ- 

 ence between the cold of ice and the heat of the sun was divided into 30 

 degrees, and these were the points of comparison for the thermometers of 

 those days. 



With regard to meteorological observations, they were instituted in the 

 year 1654, by the Grand Duke Ferdinand II. and continued by the Accademia 

 del Cimentb. They used to be taken at Florence at the Palazzo Pitti, at the 

 Giardino Boboli, and at the Convento degli Angeli ; and afterwards at 

 Cutigliano, Vallombrosa, Bologna, Parma, Milan, Warsaw, Innsbruck, &c. 

 Observations were usually made, at different hours of the day, of the state of 

 the thermometers exposed to the north and to the south ; the condition of 

 the sky, the direction of the wind, the barometric pressure, and the moisture 

 of the atmosphere. Now, if these observations taken so long ago, be com- 

 pared to recent ones, it will be seen that, after due corrections have been 

 made, or if observations be taken now with some of the best instruments of 

 the Accademia del Cimento, the meteorological conditions of Tuscany have 

 not changed. 



It was with the thermometer No. 13 that the members of the Accademia del 

 Cimento carried out their first experiments on radiant heat, which showed 

 how both the heat of burning cinders and the cold of ice are reflected, accord- 

 ing to the same law, by a concave mirror. Illustrations of these experiments 

 are . to be seen in the photograph of Galileo's Gallery, in the lunette on the 

 right hand side of the Tribujia. 



Several thermometers, similar to No. 14, were placed by the Grand Duke 

 in his rooms, in order to secure an equable temperature in all of them. 



As to thermometer No. 17, most important use was made of it for deter- 

 mining the temperatures of sick persons. The various degrees of heat were 

 shown by the sinking of little balls of different colours in proportion as the 

 temperature rose. 



At the present day we have returned to the cylindrical shape of ther- 

 memeter bulb, already used by the Accademia del Cimento. 



3745. Clinical Thermometers, made upon Dr. Phillip's 

 principle. Francis Pastorelli. 



The ball and part of the stem are filled with mercury ; above the main 

 column, separated by an air speck, is a small mercurial index ; when heat is 

 applied to the ball the column and index are driven forward ; on cooling the 

 main column only recedes, the index remains, the upper end of which indicates 

 or measures the amount of heat applied. Above the air speck the space is a 

 vacuum. 



3745a. Dr. Clifford Allbutt's Clinical Thermometers; 



Fahr. and Cent, scales ; various patterns. 



Harvey ', Reynolds, Sr Co. 



The general introduction of the thermometer for ascertaining the tempera- 

 ture of the body in disease indicates one of the chief advances in the methods 

 of diagnosis. 



Dr. Aitken used thermometers 10 inches long, and the instrument was 

 hardly met with beyond the wards of a few hospitals. In 1867, Dr. Clifford 

 Allbutt requested Messrs. Harvey, Reynolds, and Co. to make instruments 

 with a chamber anterior to the bulb, reducing the length of the tube from 



