8 
SIE J. E. W. HEESCHEL’S CATALOGUE 
mately obtained from the diagrams accompanied by micrometrical measures of position 
and distance, or from more loose and general indications contained in Lord Rosse’s 
paper in the Philosophical Transactions for 1861, the comparisons being in all cases 
made with those nebulse in my Catalogue of 1833 whose numbers stand annexed to 
them in column 2, with an italic letter appended, thus : — 
322, a R. nova; 319, a R. 3 novae. 
In cases of which latter kind it is intended to express merely that nebulae to the num- 
ber indicated, not otherwise identifiable, will be found on due search in the immediate 
neighbourhood of the place approximately set down. Lastly. The names of Professor 
G. P. Bond, Mr. S. Coolidge, and Mr. J. T. Safford in this column of the supple- 
mentary list of nebulae refer to the places of nebulae and clusters in a list of objects of 
that description discovered at the Observatory of Harvard College, obligingly commu- 
nicated to me by Professor Bond, Director of that establishment, too late for their intro- 
duction into the body of the Catalogue. 
Besides these references, in which the places set down have been adopted from the 
catalogues above mentioned, column 4 also contains synonyms or identifications of 
objects observed by myself with those contained in Messier’s lists communicated to the 
French Academy, or to the Connoissance des Temps for 1783 and 1784. These are 
cited by the number they bear in Messier’s own list, thus, M. 1, M. 2, &c. They have, 
with very few exceptions, been observed and described by myself or my Father, and their 
places here set down are given as results from our observations. In the few excepted 
cases they are taken from M. Auwers’s catalogue already spoken of. The nebulse also 
whose identity has been (sometimes satisfactorily, but for the most part very doubtfully) 
made out with objects in Mr. Dunlop’s Catalogue of Southern Nebulse, are indicated by 
the letter A, thus, A. 169, &c. In a few cases, chiefly those of nebulous stars, planetary 
nebulse, or very star-like objects, which have been set down as stars in catalogues of 
authority ; these are also referred to by name and number in column 4. 
Many of Mr. Dunlop’s nebulse are contained in Lacaille’s catalogue, as also some of 
Messier’s, but of that catalogue two objects only, not so identifiable, viz. Nos. 38 and 
40 of M. Auwers’s catalogue of Lacaille’s nebulse, have been considered as definitely 
enough described (nebuleuses sans etoiles) by that astronomer to be inlcuded in the 
present Catalogue. 
Column 5 contains the Right Ascension in time for 186(H) of each object in the 
Catalogue. When this is given to decimals of seconds, it is to be understood as having 
been brought up from the mean of the observations given in my former Catalogues, or 
from the mean of those (where not observed by myself) in Miss C. Herschel’s Zone 
Catalogue above mentioned *. When the R.A. is given only to the nearest minute or 
degree, it will of course be understood that the place is too loosely determined to render 
* In some cases a careful subsequent revision of the catalogued observations seriatim has necessitated altering 
these E.A.’s by a few decimals of a second (seldom more) after the process of reduction to 1860. In all such cases 
the alteration has been applied as a correction to Mr. Rersckiver’s figures, so as not to disturb the amounts of pre- 
cession allowed — a procedure perfectly legitimate and productive of no error. The same remark applies to col. 8. 
