298 report— 1865. 



so happen that one on each side cannot be conveniently chosen, three objects 

 (including the one to be identified) in a line will contribute perhaps quite as 

 much to finding the object sought. The column (13) in Form No. 3, headed 

 Alignment, is intended to receive three symbolical references, one being the 

 object catalogued under the symbol heading the sheet with the Arabic 



numeral at the commencement of the line, for example ; II : HE"" 4 : 



IIE P , in which HE* - represents the crater Piazzi Smyth, and this aligns 



with HE" -1 andllE* 2 . 



The wide column (14) headed "Description" scarcely needs a remark. 

 The descriptions of objects are intended to be as brief as possible, noting 

 principally their relative positions, &c. with regard to other objects. 



In order that a catalogue, such as the one now in progress, should be per- 

 fectly efficient and accomplish the object intended, it is manifest that nothing 

 should be omitted, nor should it be compiled hastily ; the labours of all pre- 

 vious selenographers should find a place, all synonyms should be inserted, 

 and references made to existing maps and drawings. With this view a por- 

 tion of each symbolic sheet of Form No. 3 is devoted to the reception of such 

 synonyms and references ; the first column (15) being intended for references, 

 in Roman numerals, to a special catalogue of objects, the descriptions of 

 which have been drawn up from careful observation with the telescope. 



The second column (lfi) in this department of Form No. 3 is intended to 

 receive an appropriate symbol, which at once indicates whether the object 

 be a crater, mountain, mountain-chain, rill, low ridge, lucid streak, or other 

 feature. For this purpose the following symbols are employed : — 



Craters and depressions are indicated by a small italic character, with an 

 index number, both inclosed in parentheses thus, (b 1 ). 



Confluent craters are thus shown, (c 1 : c 2 ). 



Ancient rings thus, (e 5 ). 



Valleys thus, all 1 . 



Mountains are indicated by a small Roman character, with an index num- 

 ber, both inclosed in parentheses thus, (a 1 ). 



Mountain-chains are indicated in the same way, with a dash under tho 

 letter thus, (a 2 ). 



These letters are not to be applied arbitrarily. To each zone of latitude 

 of 5° a character, Roman or Italic, is especially appropriated. One of these 

 letters (Italic) is printed at the foot of each column of symbols, under the 

 head of " Zones and limiting latitudes" in Form No. 2, ranging from a to s, 

 they are to be used tlras : — If a mountain be found in zone XV. or XVI., viz., 

 35° to 40° N. or S. latitude in any quadrant, the symbol pointing it out to be 

 a mountain is (h), the numbering being consecutive, a catalogue of moun- 

 tains will ultimately be formed; the same may be said of craters or any 

 other feature. 



Low ridges are indicated by an Arabic numeral, inclosed in brackets, 

 thus [2]. 



Lucid streaks in the same way with a dash under, thus [6]. 



Lucid spots by a number with a cipher below, thus [8 ]. 



Dark streaks are shown by the number having two dashes, one above, the 

 other below, thus [4]. 



Dark spots are shown by the addition of a cipher to the left and above, 

 thus [°6]. 



Hills are indicated by the symbol 1 . 



