184 PHILOSOPHICAL TRANSACTIONS. [aNNO 1782. 



An actual survey was made in the year 17SO, when the number of inhabitants 

 were 1113. There remains alive in 1780, under 10 years of age, males 155 

 females 138 = 293. From 70 to 75, males 6, females 11 = 17. From 75 to 

 80, males 5, females 8=13. From 80 to 85, males 2, females 4=6. From 

 85 to 89, males 2, females 1 = 3. 



The number of inhabitants actually surveyed 

 every 5 years for 30 years, as annexed. The n ]7 ^ ' 104 g 



increase of 48 persons in the year 1765 was 1765 1090' 



1 ■ r r •!■ 1770 1046 



owing to the ingress 01 4 numerous families 1775 K)5 _ 



into large houses, which were almost unin- 1780 1113 



habited for many years before. 



The decrease of 50 persons in the year 1770, was occasioned by the demo- 

 lishing of 9 houses, in order to open a way to the-new stone bridge built over 

 the river Severn. 



Vlll. An Experiment proposed for determining, by the Aberration of the Fixed 

 Stars, ivhether the Rays of Light, in pervading different Media, change thei 

 Velocity according to the Law which results from Sir Isaac Neivtons Ideas con- 

 cerning the Cause of Refraction ; and for ascertaining their Velocity in every 

 Medium whose refractive Density is known. By Patrick Wilson, A. M., As- 

 sistant to Alex. Wilson, M. D., Professor of Practical Astronomy in the Uni- 

 versity of Glasgow, p. 58. 



On the supposition that the refraction of light is caused by a certain action of 

 gross and sensible bodies on it, Sir Isaac Newton has demonstrated, that the 

 sines of incidence and refraction, when the rays pass out of one medium into 

 another of different density, must always be in a constant ratio. This con- 

 stancy of the ratio of the sines is agreeable to universal experience, and has been 

 called the law of refraction. On the same grounds he has also demonstrated, 

 that the velocity of the rays must be greater in the more refracting medium in 

 the inverse ratio of the sines. Ot this property of refraction however, we have 

 hitherto had no evidence in the way of experiment. The ideas entertained by Sir 

 Isaac from which this property has been deduced, though they confess their great 

 author, by a most beautiful simplicity, and by a very striking agreement with 

 fact, have yet been deemed by some persons as not perfectly authentic. His 

 contemporary Leibnitz and others have attempted demonstrations of the law of 

 refraction from principles very different, and which do not lead to the opinion of 

 the acceleration of light in the more refracting medium. At present it is pro- 

 posed to point out a method of determining experimentally the law of the 

 variation of the velocity of light, according to the change of the medium. If 

 observations shall shew this law to be agreeable to Sir Isaac's conclusions, we 

 shall then have a very strong additional evidence in favour of his principles. If, 



