III. THERMOMETRY. 257 



Thermometer in winding form, very sensitive, height 32 cm. ; 

 the spiral tube is 2 * 30 meters long. Accademia del Cimento. 



Thermometer, with balls (thernioscope). The alcohol dilating 

 by heat, the little balls fall one after another according to their 

 weight. Accademia del Cimento. 



The Accademia del Cimento was founded by Prince Leopoldo de' Medici, 

 brother of the Grand Duke Ferdinand II. , who also greatly favoured it. The 

 first assembly was held at the Palazzo Pitti ia Florence on the 18th of June 

 1657 ; and it chose for a device the celebrated motto " Provando e Ripro- 

 vando." After ten years of existence, Prince Leopold having been made a 

 Cardinal, the academy -was dissolved. 



1075a. 'sGravesande's Ball and Ring Pyrometer, for 



showing expansion. Harvey, Reynolds, and Co. 



1076. Musschenbroek's Pyrometer made in the first half 

 of the 18th century, with five different metal bars, and an autograph.. 

 Property of His Highness Prince Pless, Schloss Fiirstenstein. 



The Breslau Committee. 



The apparatus has been constructed after the description and drawing 

 given on p. 12 and Table XXX. of Musscbenbroek's "Tentamina Experimen- 

 " torum .Naturalium Captorum in Academia del Cimento, Lugduni, 1731, 

 " Pars. II." The orthography of the French, on an annexed slip of paper, is 

 that of the beginning of the last century. The instrument, which is in capital 

 condition, may therefore be considered as one of the oldest of its kind. 



1O27. Original Spirit Thermometer, of the Florentine 

 Accademia del Cimento (17th century). 



The Royal Institution of Great Britain. 



Presented to the Royal Institution by Sir Henry Holland, Barti, F.R.S. 

 1003. Photographs of Old Thermometers ; a small al- 

 cohol thermometer, with Florentine scale, and four larger ones by 

 Michelo du Crest (1754). 



Prof. Hagcnbach-BiscJwff', Director, The Physical Insti- 

 tute in the Bernoullianum, Basle. 



In these alcohol thermometers zero indicates the temperature of the cellar 

 under the Observatory of Paris, and 100 the boiling point of water. 



1070. Wedgwood's Pyrometer, invented in 1782. 



Edinburgh Museum of Science and Art* 



Dry clay when exposed to high temperatures contracts uniformly, and 

 Wedgwood believed that by the amount of contraction the temperature 

 which produced it could be measured. The instrument, however, is not 

 trustworthy. This specimen was made by Josiah Wedgwood, and presented 

 to the Edinburgh Museum by his grandson Mr. Godfrey Wedgwood. 



1O67. Wedgwood's Pyrometer, consisting of pieces of clay, 

 contracting according to the heat to which they are exposed. These 

 are afterwards slid along the gradually diminishing and graduated 

 groove in the brass plate, and so indicate the degree of heat ta 

 which they have been exposed. Robert Garner, F.R.C.S* 



4007A R 



