INTRODUCTION. XLI 



THE CHART. 



When the publication of this work had been decided on, I tried, in company with a friend at 

 the head of one of our observatories, a variety of other star-charts, to see how they would answer 

 for the purpose ; and we finally came to the conclusion that my original plan that is, on Mer- 

 cator's projection, with the ecliptic for the straight, or central, and guiding line was the only 

 eligible one. I determined, however, to construct the chart anew; and, for the purposes of 

 greater correctness, procured from London an eighteen-inch globe by Maltby & Son, "manufac- 

 tured and published under the superintendence of the ' Society for the Diffusion of Useful 

 Knowledge' ;" and from this, but chiefly from the old globe, which I had so well proved, the 

 present charts are constructed. In preparing such charts, I had no other resort than globes ; 

 for, with few slight exceptions, the published tables of the positions of stars give only their 

 right ascensions and declinations; and to convert these, by calculations, into latitudes and 

 longitudes, would have required more time than I could afford. This method of constructing 

 the charts is sufficiently accurate for our purpose. 



Indeed, I soon found that, in the publication of this work, where I had no choice of circum- 

 stances, any hope of perfect accuracy was not to be indulged; and I had to be satisfied with 

 doing the best that I could. The charts were cut on wood ; and its subsequent unequal shrink- 

 age, together with shrinkage in stereotyping, must be the excuse for some defects in the plates, 

 which the reader will discover, but which, I think, will not be found in any way to affect seri- 

 ously the results. As to the lines, themselves, of the Zodiacal Light, I did not leave one of 

 them to the risk of such mistakes as unfarniliarity with the subject might produce; but, after 

 the plain stereotype plates had been prepared, I drew every line on them myself, the boundaries 

 of the Zodiacal Light, horizons, zenith lines, &c.; and the engraver then following after, he 

 has, I believe, given them with entire fidelity. I can thus assert that, for attaining accuracy, 

 no pains-taking on my own part has been spared. 



Any one, who attempts to construct a star-chart from published materials, will find many 

 difficulties in his way. Of seven or eight of the best authorities to which I referred, as to the 

 magnitudes of stars, no two were agreed; indeed, the discrepancies were so great, that the more 

 I consulted, even standard authorities, the more embarrassed and uncertain I became ; and I 

 finally came back to my old 9-inch globe, which I had so long and thoroughly tested, and on 

 the general accuracy of which I knew I could rely. In my charts, Bellatrix is, however, put 

 down, by some inadvertence, as a star of the first, instead of the second magnitude; No. 8 Ceti 

 has, from the same cause, a latitude less by 40" than it ought to have. Doubtless there are 

 many other defects in the charts, respecting which I can only say that I have done the best foi= 

 accuracy that my circumstances would allow. I trust, however, that none will be found of 

 sufficient importance to impair any one's confidence in the results here offered to the public. 

 The numbers given to the stars, when such are adduced, are those which I found on the 9-inch 

 globe. 



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