6 
SIR J. E. W. HERSCHEL’S CATALOGUE 
many instances, a change in the order of R.A., and a consequent erasure and interlinea- 
tion in the MS. The introduction, too, of the other nebulae (those of M. Auwers’s cata- 
logue of “ novae,” those communicated to me for insertion by M. D’ Arrest, and those 
noticed by Lord Rosse in his memoir of 1861, amounting altogether to 433 objects) 
necessitated many more interlineations, often occurring very inconveniently, two or three 
together, in a way to disfigure the MS. considerably. Unfortunately, too, in the MS. 
itself the column headed “ No. in the Catalogue,” which I had intended to have been 
left blank till all the rest of the work was completed, had been filled in by the trans- 
criber with a series of numbers in regular progression, from 1 to 4629, the actual num- 
ber of lines of which it then consisted. This made it necessary to renumber the whole 
ab initio in red ink, striking out the former numbers, and thus producing a still more 
unsightly appearance. Under these circumstances, I debated whether or not to recopy 
the whole. But, to say nothing of the sacrifice of time (since I could have entrusted it 
to no other hand), I believe it impossible to copy so voluminous a mass of figures and 
abbreviated writing without numerous errors. And being satisfied, from the repeated 
and careful revision it has undergone, of its present correctness, and equally so that with 
ordinary care on the part of the compositor (should the Council of the Royal Society 
decide on printing it) no mistake can arise from any of the alterations and interlineations 
it contains, I have decided in favour of presenting it as it stands, with the exception of 
two sheets which it was absolutely necessary to recopy owing to the extreme closeness 
of the interlineations, the smallness of the writing, and the transpositions needed. 
These have each been twice carefully read with the original. 
In presenting to the Royal Society this Catalogue, it will be accompanied by the 
following series of records and documents which it may become desirable hereafter to 
refer to in elucidation of any point which may arise respecting the history or reduction 
of such of the objects as occur in my Father’s classes and numbers printed in the Philo- 
sophical Transactions, viz. — 
1st. A series of “ register sheets ,” in which are entered up all the observations of each 
nebula or cluster copied verbatim from the sweeps, the nebulae, &c. being arranged in 
the order of their dates of discovery. These are the “ register sheets ” referred to in 
the notes on this Catalogue, and cited by their general (i. e. current) number , as H, 1 ; 
H, 2 ; . . . H, 2508. 
2nd. A similar set of register sheets of all the observations of each of Messier’s 
nebulae, arranged according to Messier’s numbers. 
3rd. A general index of the 2508 nebulae in classes and numbers, to find the “ general 
number ” of each to facilitate reference to the register sheets. (This index was drawn 
up by myself.) 
4th. An index list of the same nebulae, &c. arranged according to the “general 
number,” to find the class and number of each. 
5th. A more complete ditto ditto, containing also the rough approximate R.A. and P.D. 
of each object for 1800, and the determining stars as in the Philosophical Transactions. 
6th. A catalogue in zones of P.D. of all the said nebulae and clusters arranged in each 
