C3(J PHILOSOPHICAL TRANSACTIONS. [^ANNO J 762. 



the mouth was surrounded by a radiated substance, about the size of a silver pen- 

 ny, thicker and more callous than the coats of any other part. The internal 

 aperture of the anus was composed of fibres interwoven with one another. From 

 the apex to the base, on each side, descended obliquely, and winding, a smooth, 

 solid body, in width about one fifth part of an inch, part of which separated in 

 the examining, so that it is but imperfectly represented in the drawing. We can- 

 not give a clearer idea of this body, than by saying, that it had greatly the ap- 

 pearance (except in size) of one of the small intestines, and was attached to 

 the interior surface of the main body, much in the way as they are to the me- 

 sentery. 



XCin. Results of Observations of the Distance of the Moon from the Sun and 

 fixed Stars, made in a voyage from England to the island of St. Helena , in 

 order to determine the Longitude of the Ship, from Time to Time ; with the 

 whole Process of Computation used on this Occasion. Bij the Rev. Nevil Mas- 

 kelyne, M.A.,F.R.S. Dated St. Helena. Sept. Q, 1761. p. 558. 

 During the course of his voyage from England to St. Helena, Mr. M. made 

 frequent observations of the distance of the moon from the sun and fixed stars, 

 in order to determine the ship's longitude : and, as from their agreement with 

 each other, he conceived it will be allowed, that the longitude may in general be 

 ascertained by this method to sufficient exactness for nautical purposes, he thus 

 communicated to the r. s. the results of his observations. He also delivers 

 the whole process of computation, which he used in deducing the longi- 

 tude from an observation, wherein he included several useful rules of his own 

 investigation, which he apprehends render the calculation not only much shorter, 

 but also much less intricate than it was before. 



The time being determined by an altitude of the sun or a star, and the distance 

 of a proper star from the moon's limb, or the distance of the sun and moon's 

 nearest limbs in the first and last quarter, being carefully observed, the longitude 

 may thence be found without any other observations ; and this is the method 

 proposed by the late Dr. Halley, which certainly deserves to be highly esteemed 

 for its great simplicity, and the small number of observations which it requires. 

 Yet Mr. M. owns himself of opinion with the Abbe De la Caille, that it will be 

 more convenient at sea to require the aid of more observations, which is the me- 

 thod Mr. M. constantly practised during his voyage, having always two observers, 

 who were ready, one to take the altitude of the star, and the other of the moon's 

 upper or lower limb, at the instant he spoke when he had made the observation of 

 the distance of the star from the moon. 



Mr. M. can therefore answer from his own experience, both that the method 



