ON MAPPING THE SURFACE OF THE MOON. 259 



14. The middle of three craterlets east of IV A^l 2"-85, mag. 0-18. 

 tl5. The ISr.E. of three craterlets east of IV A^ 1. 

 These craterlets lie in a line from the east border of IV A^^ to the rocky 

 border of Ptolemseus. On Sept. 22, 1864, these three were recorded, with a 

 probable fourth. B. & M. give six, and say, in ' Der Mond,' p. 346, " a row 

 of six craters." 1865, Jan. 5, fotir are quoted by Mr. Freeman of Mentone, 

 with two very small ones. 1866, Feb. 22, I found five. The additional 

 ones are IV A^^^ ^^^^ IVA^^9_ 



**16. The mountainous west border of Ptolemaeus. Lohrmann, Sec. 1. 16. 

 **17. A mountain on the west border of Ptolemajus forms a terrace inter- 

 mediate in altitude and position between the high rugged land at the 

 N.E. of Albategnius and the smooth surface of Ptolemfeus, and 

 has a slight, but very perceptible, depression on its summit, Avhich is 

 not unlike a tableland. West of it is the deep hollow IV A^ ^ ' . 

 tl8. A smaU craterlet N.E. of IV A^ '^ 

 tl9. A small craterlet N'.E. of IV A^ ^^ 

 These two craterlets complete the record of the crater-row from IV A^ 

 to IV A^ ^''. Mr. Knott considers that IV A^ '^ is not a craterlet, but only 

 a rise in the groimd, which produces a craterlike appearance. 



This crater-row may now be considered as well determined, and with the 

 dimples IV A^ ''', IV A^ ^, will constitute a crater-rill, according to Schmidt, 

 although not found in his catalogue. It is noteworthy that it occurs on the 

 line of cliffs extending from Halley to Ptolemaeus, which is broken by. 

 IV A^', IV A^^. IV A^^- is common to two lines of cliffs, which cross 

 each other nearly at right angles. The magnitudes of IVA^'^, IV A^ , 

 IV A^ 19 ^^r^YQ not been determined nor estimated. The length of the crater- 

 rill from IV A^ ''^ to IV A^ '^ inclusive is 1.5"-22. It is not in Lohrmann. 

 i20. A fuiTOW on the interior slope of the S.E. rim of IV A^^ length 

 10"-94. 

 This furrow was discovered on the 6th of December, 1864, by the Rev. 

 T. W. "Webb, who thus mentions it in a letter under date of the 7th of 

 December, 1864. Speaking of the row of craters extending from IV A^ 

 to Ptolemy, he says, " There are but four, or at most five craters in their 

 [B. & M.'s] row of six. I could readily count them but for the great 

 agitation of the air ; the S.W. one, which seems to be Albategnius f of 

 the map, is the largest ; they decrease somewhat towards Ptolemaeus. The 

 direction S.W. is carried on by a furrow (I presume one of your dimples) 

 through the wall, and visible on its interior slope to the junction of the 

 two subcraters on the S.W. side of X (IV A^^)." 



On the 5th of January, 1865, Mr. Freeman at Mentone, the Alpes Mari- 

 times, examined this locality, but could not find the furrow. Of the crater- 

 row he says, " The four were too nearly in a direct line with IV A^ ^ to 

 enable a furrow witliin the ring of 235 (L.) to connect them." 



On February 22, 1866, I obtained at Hartwell, with the equatoreal of 

 o-9-inches aperture, a view of Mr. Webb's furrow; my observation is thus 

 recorded : — ■" I saw also distinctly Mr. Webb's furrow on the interior of the 

 S.E. border of X (IV A^ ^), which is a continuation of the crater-row, in which 

 at least there are five craters." 



The existence of this furrow is accordingly confirmed, although it would 



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