130 PHILOSOPHICAL TRANSACTIONS. [aNNO 1674. 



Of Parhelias. By M. Hevelius. N° 102, p. 26. 



On Feb. 5, l674, N. S. near Marienburg in Prussia, I saw the sun, in a sky 

 every where serene enough, being yet some degrees above the horizon, and 

 shining very bright, yet lancing out very long and reddish rays, 40 or 50 de- 

 grees toward the zenith (as in fig. 1, pi. 6.) Under the sun towards the horizon, 

 there hung a somewhat dilute small cloud, beneath which there appeared a 

 mock sun of the same size, to sense, with the true sun, and under the same 

 vertical, of a somewhat red colour. . Soon after, the true sun more and more 

 descending to the horizon, towards the said cloud (as seen in fig 2), the spuri- 

 ous sun beneath it grew clearer and clearer, so as that the reddish colour in that 

 apparent solar disk vanished, and put on the genuine solar light, and that the 

 more, the less the genuine disk of the sun was distant from the false sun : till 

 at length the upper true sun passed into the lower counterfeit one, and so re- 

 mained alone; as appears in fig. 3. 



This appearance being unusual, I took the freedom of imparting it tin to you, 

 especially since here the mock sun was not found at the side of the true sun, as 

 it is wont to be in all parhelias seen by me, but perpendicularly under it ; not 

 to mention the colour, so different from that which is usual in mock suns ; nor 

 the great length of the tail, cast up by the genuine sun, and of a far more vivid 

 and splendid light, than parhelias use to exhibit. Upon this appearance there 

 soon followed here an exceedingly intense and bitter frost, whereby the whole 

 bay was frozen up from this town of Dantzic, as far as Hela in the Baltic sea, 

 which lasted till the 25th of March, and the bay was frozen so hard, that with 

 great safety people run out into it with sleds and horses, for several of our 

 miles. 



Concerning the famous Kepler's^ Manuscripts , with some Considerations about the 

 Use of Telescopic Sights in Astronomical Observations. In a Letter from 

 M. Hevelius. Abridged and Translated from the Latin. N° 102, p. 27. 



I perceive that all your countrymen do not agree with me in opinion, on 



the subject of sights in astronomical instruments, which I have treated of in the 



* John Kepler, one of the best astronomers and mathematicians of the l6th century, was born 

 in Wirtemburg, in 1571 ; and obtaining a good education at Tubingen, he became professor of 

 matliematics at Gratz, In 16OO he joined Tycho Brahe, then in Bohemia, as an assistant, by whom 

 he was introduced to the emperor Rudolphus, who honoured him with the title of his mathematician, 

 Kepler completed the astronomical tables which Tycho had left unfinished, and published them by the 

 name of Rudolphine Tables. In l6l3, at the assembly of Ratisbon, he assisted in tlie reformation of 

 the calendar. After many difficulties and privations, he died in that city in 1630, at 59 years of age. 



