354 PHILOSOPHICAL TRANSACTIONS. [aNNO J 783. 



of an earthquake was felt in several parts of Wales, by many persons, though 

 not generally. At Mold, in the county of Flint, it was distinctly perceived by 

 a gentleman, at that time in a house quite out of the town, and seemed attended 

 with a rumbling noise, like a carriage going over a pavement; and at the same 

 time some China cups and saucers rattled very much, that were on a table in the 

 room with him. At the palace, at Bangor, it was perceived by all the bishop's 

 family at about 3Q minutes past eight o'clock, with the same kind of rumblino- 

 and a double vibration. Many other persons in that neighbourhood were sen- 

 sible of it. In many places in the isle of Anglesey it was strongly felt; at Bodor- 

 gan, the seat of Owen P. Me) rick, Esq., it was thought by the family that a 

 carriage had driven up to the door. In answer to some inquiries made, Mr. L. 

 received the following account from an ingenious friend, who was concerned in 

 the great copper mine at Paris Mountain, and was at that time within a mile of 

 the mine at his own house. 



" I perceived the earthquake to begin at Amlwoh at 40 m past S o'clock at 

 night, on Saturday the 5th of October. The shock was great and alarming. 

 The house was shaken terribly, and underwent several vibrations for the con- 

 tinuance of near a quarter of a minute. I thought it moved from n. e. to s. w. 

 but was not certain. It was attended with a rumbling noise, as loud as thunder, 

 and like it just before it ceases." 



Fill. Of a Neiv Eudiometer. By Mr. Cavendish, F. R.S. p. 106. 

 Dr. Priestley's discovery of the method of determining the degree of phlo- 

 gistication of air by means of nitrous air, has occasioned many instruments to be 

 contrived for the more certain and commodious performance of this experiment; 

 but that invented by the Abbe Fontana is by much the most accurate of any hitherto 

 published. There are many ingenious contrivances in his apparatus for obviating 

 the smaller errors which this experiment is liable to ; but the great improvement 

 consists in this, that as the tube is long and narrow, and the orifice of the funnel 

 not much less than the bore of the tube, and the measure is made so as to 

 deliver its contents very quick, the air rises slowly up the tube in one continued 

 column ; so that there is time to take the tube off the funnel, and to shake it 

 before the airs come quite in contact, by which means the diminution is much 

 greater and much more certain than it would otherwise be. For instance, if 

 equal measures of nitrous and common air are mixed in this manner, the bulk of 

 the mixture will, in general, be about one measure; whereas, if the airs are 

 suffered to remain in contact about J- of a minute before they are shaken, the 

 bulk of the mixture will be hardly less than 1 measure and -,*„, and will be 

 very different according as it is suffered to remain a little more or a little less 

 time before it is shaken. In like manner, if, through any fault in the apparatus, 



