'J&i 



CATALOGUE. — PHYSICAL OPTICS, 



ovil ; in horizontal diameter the shorter ; the parhelia a 

 dejree or two beyond it. 



Maraldi on two meteors. A. P. 1721. 231. 

 H.4. 



The internal tangent arc appeared like two portions hav- 

 ing their centres in the lateral parhelia. Observes, that 

 there are always delicate and almost invisible clouds when 

 they appear : the wind N. E. or E. and a little frost, suc- 

 ceeded by a milder air. Some slender melting snow fell 

 two dayt after. v 



Dobbs on a parhelion seen in Ireland. Pli. fr. 

 1722. XXXll. 89. 



Three parhelia without halos. Two inverted arches 

 above. 



.Whiston. Ph. tr. 1727. XXXV. 257. 



The halo was touched by two curves above and by one 

 below : the lateral parhelia were without the halo, but not 

 in the intersection of either of the tangent arches produced 

 with the horizontal circle : there was a small portion of a 

 secondary halo about one third larger than the primary: 

 perhaps belonging to the tangent arch. There were two 

 anthelia, further apart than the parhelia. IVIarch i, Rafter 

 10. Kensington. The two tangent curves appeared to be in- 

 dependent of each other, one only appearing at first. 



Academy of Bezieres. /. P. 1729- H. 2. 



June, from 10 to 12. H.'JO° 3l'. 



Musschenbroek. Ph. tr. 1732. XXXVIf. 

 357. 



A white horizontal circle above the sun, 58° is' in dia- 

 meter, crossed by the coloured halo. At 50° 30' from this 

 crossing was a parhelion in the horizontal circle. Apr. as, 

 from 1 p. 10 to I p. 11. H. 45° 3o', externally. 



Scliultz. Coll. Acad. VI. 270. Mentzelius. 



301. Others. 445. 

 Trisch on a halo. M. Berl. 1734. IV. 64. 



Some anomalous arcs passing through the sun. 



Diifay. A. P. 1735. 87- 



Chiefly from 27 observations of Musschenbroek in 1734. 

 The thin clouds forming them are always higher than the 

 common clouds. N. l.H. 23° li' internally, lunar. N. 2. 

 H- 23^. A second arc was seen near the zenith, its dia- 

 meter varying from 24° to 30°, 28°i, and 27°|, being 

 greatest ai. 1 1 o'clock, in January. The halo changed also 

 from 23° disunce to 19° 50', 19°, and 18° 30". N. 3. 

 More than half the circumference of an inverted arc touch- 

 ing the first halo, and of the same curvature with it : the 

 circle about the zenith appeared of a constant diameter 



while the sun's altitude varied i this altitude was Aout 

 1 4°i. N. 4. A train of light ascended from the sun. N. 7. 

 Lastcd^l! day, June 17, exactly 23°i radius. N. 8. Ex- 

 actly 23°i, from the red edge to the centre of the sun, about 

 1' I bioad. N. 9. H. 22°. 



Grandjean de Fouchy on a paraselene. A. P. 

 1735.585. 



The moon in a cross, 20° altitude. 



Neve. Ph.tr. 1737. XL. 50. 



At Petersburg. 



Weidler. Ph. Ir. 1737- XL. 54. 



Sun's altitude 15°1. Ext. H. 45°f Lateral parhelion at 

 20° exactly. 



Foikes on three mock suns. Ph. tr. 1737. 



XL. 51). 

 Weidler de parhelils anni 1736. 4. \Vittemb. 



1738. M. B. 



Ace. by Stack. Ph. tr. 1740. XLI. 459. 



Bad theory. 



Weidler de anthelio. Ph. tr. 1739. XLI. 

 209. 



This was an appearance in the north, at J p. g. I8 Jan. 

 1738, of two arcs crossing at an angle of 00°, with a halo 

 2°i horizontally, and i°i vertically in diameter, red within. 

 Snow fell soon after. A similar appearance it related by 

 llevelius de Mercurio in sole viso. 



Mills on parhelia seen in Kent. Ph.tr. 1742. 



XLII. 47. 

 Gostling. Ph. tr. 1742. 60. 



December. From sunrise till noon. 



Halos and parhelia seen once or twice a 

 week in Hudson's bay. Middleton. Ph.tr. 

 1742. XLIL 1.57. 



Lacroix. A. P. 1743. H. 33. 



Says the horizontal band was coloured ; the tangent are 

 nearly straight. 



Two suns at VVilna. A. P. 1745. H. 19. 

 Grischow on lunar circles and paraselenae. 

 Ph. tr. 1748. XLV. 524. 



The two inverted arches concentric with the zenith. 



Arderon. Pli.tr, 1749 XLV1.203. 



A halo surrounding the zenith, 1 1 July, s P. M. Appears 

 from the figure to be about j° or 8° in diameter ; the sun's 

 rays were seen shining through the cloud. 



