258 SEC. 8. HEAT. 



1078. Early Pyrometer (by Funiey). 



The Council of King's College, London- 



1079. Dani ell's Pyrometer, employed in researches by 

 Professor Daniell. The Council of King's College., London. 



lO52a. Original Air Thermometer, by M. Renault. 



College of France. 



1000. Thermometer. " The Great Pyramid temperature 

 scale, and its standard reference point of 50 P." With a map of 

 the world to illustrate the advantages of this standard. 



Prof. Piazzi Smyth. 



This consists of a large table thermometer, graduated according to the in- 

 dications of the Great Pyramid system of standards ; firstly, by colours into 

 fifths of the distance between freezing and boiling of water, and then each 

 fifth into 50, or 250 for the whole distance. 



A map of the world on an equal-surface projection accompanies the 

 thermometer, and exhibits the mean temperature of the whole earth's surface 

 according to the Great Pyramid scale ; illustrating also the territorial and 

 international advantages to all civilised nations of adopting the mean tem- 

 perature standard of the Great Pyramid, viz., 50 Pyr. or 68 Fahr., as the 

 temperature reference standard for all human purposes, scientific, social, 

 and commercial. 



1001. Legible Spirit Thermometers, with line at above 

 and below the proper temperature of a room, so that the degree 

 can be read off at a long distance, at the opposite side of a large 

 room, or at the ceiling, for experiments in ventilation. 



Peter Hinckes Bird, F.R.C.S. Land. 



1002. Apparatus for determining the Boiling Point of a 

 small quantity of Fluid. 



The Secondary Government School, Assen (Netherlands). 



In this simple apparatus, constructed after the design of Dr. A. Van Hasselt, 

 (teacher at the school for middle-class education at Assen), the small tube is 

 filled for the greater part with mercury ; the remaining space with the fluid. 

 The tube is then turned upside down into a small beaker-jar, which is also 

 filled with mercury ; part of this must be removed until the quantity left rises 

 about one or two centimetres above the bottom of the jar. When the appa- 

 ratus has been placed in the large beaker -jar, water or oil is poured into the 

 latter, so that the tube is quite immersed. The jar is then heated, agitating 

 the fluid meanwhile with a moving apparatus. 



The millimetre scale serves to determine the height of the fluid in the larger 

 jar, together with the difference between the position of the mercury in the 

 tube and that on the outside of it. In determining this difference, the pressure 

 of the fluid in the larger beaker-jar and the barometric height must be taken 

 into consideration. 



To know whether a fluid is homogeneous, two experiments must be made, 

 one with a fluid Avhich is partially evaporated. In both cases the results 

 must be the same. 



When the vapour of the fluid in the tube has the pressure of one atmosphere 

 the boiling point of the fluid must be observed. 



