'278 PHH.OSOPHICAL TRANSACTIONS. [ANNO ]782. 



XIX. An Attempt to make a Thermometer for measuring the Higher Degrees oj 

 Heat from a Red Heat up to the Strongest that Vessels made of Clay can sup- 

 port. By Josiah Wedgwood.* p. 305. 



A measure for the higher degrees of heat, such as the common thermometers 

 afford for the lower ones, would be an important acquisition, both to the philoso- 

 pher and the practical artist. The latter must feel the want of such a measure 

 on many occasions ; particularly when he attempts to follow, or apply to use, 

 the curious experiments of Mr. Pott, related in his Lithogeognosia, and other 

 modern writers on similar subjects. When we are told, for instance, that such 

 and such materials were changed by fire into a fine white, yellow, green, or 

 other coloured glass : and find that these effects do not happen, unless a particular 

 degree of fire has fortunately been hit upon, which degree we cannot be sure of 

 succeeding in again : — when we are disappointed, by having the result at some 

 times an unvitrified mass, and at others an over-vitrified scoria, from a little de- 

 ficiency or excess of heat : — when we see colours altered, not only in shade but 



* This ingenious and respectable gentleman died the 3d of Jan. 1795, at Etruria, in Staffordshire, 

 at 6"4 years of age. Mr. W. was the younger son of a potter. He derived little or no property from 

 his father ; but became, by his elegant manufactories, the maker of his own fortune, and the bene- 

 factor of his country to an incalculable extent. His many discoveries of new kinds of earthen wares 

 and porcelains ; his studied forms and chaste style of decoration ; and the correctness and judgment 

 with which all his works were executed, under his own eye, and mostly by artists of his own form- 

 ing, completely turned the current of this branch of commerce in favour of England, which before 

 imported the finer earthen wares from the Continent. But by Mr. W.'s ingenious endeavours, and 

 through his example, this country has ever since exported such wares to a great annual amount ; the 

 whole of which is drawn from the earth, and from the industry of the inhabitants ; while the na- 

 tional taste has been improved, and its reputation greatly raised in foreign countries. Mr. W. was 

 also commendably known in the walks of philosophy : besides his ingenious mechanical contrivances, 

 and philosophical arrangements and operations, through which his private manufactory had the effect 

 of a public work of experiments ; his communications to the a. s. (of which learned body he became 

 a member about the year 178+,) show a mind enlightened by science, and contributed to procure 

 him the esteem of all scientific men. Besides the above paper, other ingenious and useful commu- 

 nications of his appear in the Phil. Trans, volumes 73, 7\, 76, and 80. Mr. W. was the proposer 

 of the Grand Trunk Canal, and the chief agent in obtaining the act of parliament for making it, 

 against the prejudices of the landed interest, then very powerful. That canal, 90 miles in length, 

 unites the rivers Trent and Mersey ; branches have been made from it to the Severn, to Oxford, and 

 to many other parts ; and it has also a communication with the Grand Junction Canal from Braun- 



ston to Brentford, &c. Mr. W. having very honourably acquired a large fortune, his purse was 



always open to the calls of charity, and to the support of every institution for the public good. To 

 his relations, friends, and neighbours, he was endeared by his many private virtues ; and he has 

 been deeply regretted by his country, as the able and zealous supporter of her commerce, and the 

 steady patron of every valuable interest of society. Mr. W.'s merits have also otherwise contributed 

 to the benefit of futurity ; having reared and left behind him a family, whose virtues and useful in- 

 genuity do so much honour to his paternal care in their education. Other particulars of Mr. W. s 

 life and works may be seen in the Gentleman's Magazine for the year 1795, vol. 6"j, p. 84. 



