456 PHILOSOPHICAL TRANSACTIONS. [aNNO 1754. 



by Mens, de la Caille; from which he concludes, that the horizontal parallax of 

 that planet, at the time of its opposition to the sun, is 1T\". 



And according to the ratio of the distance of the sun and Mars from the earth 

 at that time, he concluded the horizontal parallax of the sun to be about 10^". 

 This is what he had been able to conclude from Dr. B.'s observations of Mars, 

 with respect to the parallax of the sun. Having made the same calculations 

 from his own observations, and those of other astronomers, which he could col- 

 lect; he found very nearly the same parallax of the sun, by taking a medium 

 among all the observations of each astronomer, 



^LXVIL Description of a Piece oj" Mechanism contrived by James Ferguson, 

 for exhibiting the Time, Duration, and Quantity, of Solar Eclipses, in all 

 Places of the Earth, p. 520. 



This machine may be seen described in Mr. Ferguson's Astronomy, art. 405, 

 where he calls the machine an eclipsareon, the figure of which is exhibited in 

 pi. ] 3 of that book. 



LXFIII. On the late Hard Weather. By the Rev. H. Miles, D. D., F. R. S. 



p. 525. 



This paper contains a few remarks on the very cold weather in Feb, 1754. 

 The coldest day was on the 6th, about 7 in the morning, when the thermometer 

 was at 15°. He observes that the time of the greatest cold, is usually from an 

 hour to an hour and a half before sun-rise. 



LXIX. A Catalogue of the 50 Plants from Chelsea Garden, presented to the 

 Royal Society by the Company of Apothecaries, for the Year 1753, pursuant 

 to the Direction of Sir Hans Sloane. p. 528. 



This is the 32d presentation of this kind, completing to the number of l6oo 

 different plants. 



LXX. An Account of some Experiments on a Machine for Measuring the Way 

 of a Ship at Sea. By Mr. J. Smeaton, F. R. S. p. 532. 



In the Philos. Trans. N° 39 1 , Mr. Henry de Saumarez gives an account of a 

 machine for measuring a ship's way more exactly than by the log. This machine 

 consists of a first mover, in the form of the letter y. On the 2 arms of the 

 Y are fastened 2 vanes, inclined in such a manner that when the y is hauled 

 through the water by a rope, fastened to its stem or tail, it may turn round, and 

 of consequence endeavour to turn the rope round. The other end of the rope, 

 being fastened to the end of a spindle capable of moving freely round, will be 

 made to do so by the rotations of the y, communicated to the rope. A motion 



