VOL. II.J PHILOSOPHICAL TRANSACTIONS. 207 



t 



toward the tail. The harping irons are like those which are usual in England 

 in striking porpoises, but of excellent metal that will not break, but bend 

 about a man's hand. To the harping iron is made fast a strong flexible rope, 

 and into the socket of that iron is put a staff, which, when the whale is struck, 

 comes out of the socket ; and when the whale is something quiet, 4;hey haul 

 up to him by the rope, and so strike into him another harping iron, or lance 

 him with lances in staves till they have killed him. I hear not that they have 

 found any spermaceti in any of these whales ; but I have heard from credible 

 persons, that there is a kind of such as have the sperma at Eleutheria, and 

 others of the Bahama Islands, where also they often find quantities of amber- 

 gris, and that those have great teeth, which ours have not, and are very 

 sinewy. 



To find the Numher of the Julian Period, by M. de Billy's Method ; 

 with the Demonstration of that Method. By Mr. John Collins,* 

 F. R. S. iY" 30, p. 568. 

 This method was given in these Transactions, No. 18, and is thus : 



{Solar 1 p , 1 7 /'4845x 



Lunar -> ^^ [ by -l 4200 I Then divide 

 Indiction 3 ^6qi6J 



the sum of the products by 7980, the Julian period; the remainder of the 

 division, without having regard to the quotient, will be the year required. 

 Concerning the demonstration, Mr. John Collins, now a member of the Royal 

 Society, communicated what follows, viz. 



That the Julian period is a basis whereon to found chronology not liable to 

 controversy, as the age of the world is ; and it is the number abovesaid, to wit 

 7980, which is the product of the 28th solar cycle, 19th lunar, 15 th indiction. 

 The problem may be thus proposed generally : 



Any number of divisors, with their remainders after division, being pro- 

 posed, to find the dividend. 



This is thus proposed in this general manner, but is no new problem, and was 



* An eminent accountant and mathematician, bom near Oxford in l624. Besides many papers 

 in the Phil. Trans, he pubUshed a number of useful works on a variety of subjects, mathematics, 

 navigation, astronomy, trade, commerce, &c. also editing the works of many otlier authors, 

 which he procured to be printed, as those of Barrow, Brouncker, Pell, &c. Mr. Collins was also very 

 .useful to the Royal Society, &c. in conducting a literary correspondence witli the most learned men 

 of those times, both at home and abroad, as Barrow, Newton, Wallis, Leibnitz, &cc. particularly 

 in the famous dispute concerning the invention of Fluxions between Newton and Leibnitz, the let- 

 ters passing chiefly through Collins's hands, and published in his name in 1712, under tlie title of 

 Commercium Epistolicum. He died in l683, at 59 years of age. 



