Page:Proceedings of the Royal Society of London Vol 1.djvu/394

Rh {| So that by the result of 47 observations, the result is ‘2"‘52; and Dr. Brinkley adds, that from the conﬁdence which he has now ac- quired in his instrument, he has no doubt that the annual parallax exceeds 2".
 * Ann. Par.
 * The ﬁrst seven observations were made near opposition, the next eight near conjunction
 * The comparison of these gave a result of
 * 2'18
 * The next set were seven at opposition, and eight at conjunction
 * giving
 * 3 06
 * The last set Eight at opposition, and eight at conjunction
 * gave
 * 232
 * 3) 7-56
 * }
 * The last set Eight at opposition, and eight at conjunction
 * gave
 * 232
 * 3) 7-56
 * }
 * 3) 7-56
 * }
 * }

This letter also contains some remarks upon refraction with the co-latitude of the Dublin Observatory, as deduced by means of dif; ferent formulae. From these it appears, that the agreement by De- lamhre's tables is nearer than by Dr. Bradley‘ s own formula ; but that Dr. Bradleyr‘s formula, by means of a slight correction, gives a table preferable to that of Delambre.

Dr. Bradley's is

We x tang. (zen. dist. -— 3 Refr.) 1" mm" 400

29-6 X 350 4 "6 Dr. Brinkley’s corrected formula

. ht. barom 500 ' t. . d. —- " . ._..______' . . 56 9 x ang (zen lst 3 2 Refr) x 296 +450 + 6

With a view to understanding more fully the structure of the Squalus maximus, of which Mr. Home has lately published an account, he has examined with attention that of the Squalus acanthius, which appears to resemble it closely in its internal structure, and has the advantage of being very easily obtained upon the Sussex coast, where it is very common.

After describing minutely the external organs of generation in both male and female, the author traces the progress of the ovaria from the time that the yolks are no larger than peas, till they become as large as walnuts, when they pass into the oviduct. The number of yolks differs in diﬁ'erent ﬁsh; and even in the same ﬁsh Mr. H. has seen ﬁve yolks in one ovarium and only two in the other. The oviducts then enlarge, and become exceedingly extended, and divided by contraction of its coats into three cavities, the last of which is ten inches in length, and is that in which the eggs are retained till the young ﬁshes are formed, and capable of taking care of themselves.