160 C. EK. Burroy.—Physical Observations of Mars. 
of the dusky streak which originates at Trouvelot Bay, shown in many of my 
sketches, and we may therefore consider that its real existence is placed beyond 
doubt. The streak proceeding from Huggins Bay is perhaps faintly indicated. 
Part of Oudemann Sea is visible, also Maunder Sea. Hooke Sea and Burchardt 
Land, as well as the southern snow spot, are distinctly shown; and Noble Cape is 
also well-defined. 
No. 18. Longitude=212°. 1879, Nov. 11. 10° 59™ to 11" 40" G.M.T. This 
drawing, made almost at the same absolute time as No. 17, differs from it in a 
remarkable manner, omitting the streak from Trouvelot Bay, and showing one 
which originates in the neighbourhood of Gruithuisen Bay (Green) and connects 
it with a diffused shade bordering the Arctic Circle. Huggins Bay and Oude- 
mann Sea are connected by a dusky streak, the southern end of which is shown in 
No. 17. Maunder Sea is very distinct. 
Fine definition with power 220 (an achromatic triplet) on the 8-inch reflector. 
No. 19. Longitude=215°. 1879, Nov. 13. 12" 85™ to 12" 52™ G.M.T. The only 
feature of this drawing which requires particular notice is the streak running 
northwards from Gruithuisen Bay, already remarked upon. Hooke Sea is drawn 
too near the eastern limb. The boundary of the north snow spot was a very 
distinct dark line. 
Same instrument used, and power 270. 
No. 20. Longitude=216°. 1879, Dec. 17. 8" 42™ to 9" 12" G.M.T. The same 
part of the planet is here presented to view at a date five weeks later than that of 
Nos. 18 and 21, and as seen with a much more powerful instrument, the 12-inch 
equatoreal reflector, furnished with R.A. movement, and armed with magnifying 
powers of 408 and 514 diameters. Definition was at times extremely fine with 
these powers. 
Noble Cape is exceedingly distinct. Trouvelot Bay and Huggins Bay each form 
the origin of dusky streaks similar to, and probably identical with those already 
described. The latter streak was sharply defined on both sides. The southern side of 
Maraldi Sea was very ill-defined compared with the northern, which was hard and 
irregular. I could not seize the positions of the minute irregularities so as to draw 
them,*for they flitted into and out of sight very rapidly with the undulations of the air. 
The northern snow was bounded by a dark and very narrow line,+ repeatedly 
seen with power 514, and appeared very small and white. The shadings were 
visible closer to the western limb than to the terminator. The penumbral edge of 
the terminator was visible, of a bluish tinge, which, as I satisfied myself, was not 
due to the eyepiece. The preceding, or fully illuminated limb, appeared as sharp 
as the edge of a hole punched in metal. The streaks and the faint shading seen 
in the position of Oudemann Sea were decidedly blue. 
* The general appearance is shewn in the Drawing. 
+ This line was not perfectly sharp, and was rather tangential to than concentric with the snow spot. 
