on Magnetic Needles. 341 



lished of the voyage undertaken to Hudson's Bay in 1746, in 

 search of a noilh-west passage. I should not deem this cn- 

 cumstance worth noticing, but for the very extraordniary ac- 

 knowledgement that it has pleased Dr. De Sanctis to make ot 

 the source of his experiments: "lam," says the Doctor, m- 

 debted for the idea of these experiments to ihe simple observa- 

 tion of Captain Ellis, who, meeting ice mountains * in Hud- 

 son's Bay, saw his needles sluggish at their approach ; and 

 says, he restored them to their former activity by warmth. 

 Far from reasoning on the circumstances, he has lite air of r<> 

 peatljig the fact as a kind of mysterious accident., Wliat a dit- 

 ference between that rough transient observation and the re- 

 sults W6' have obtahied ! Sach is the progress of science, 

 aided by time, zeal for experiment, and skill in observing ! _ 



After this representation, it will scarcely be credited, with- 

 out referring to the Voyage f, that so far from not haying rea- 

 soned on the circumstance of the compasses having lost their 

 magnetic properties, and of having the air of repeating the tact 

 as a kind of mysterious accident, Mr. Ellis actually occupied 

 above eight pages t with conjectures, reasonings and hj^iotheses 

 concernmg its cause. An attempt was made to restore the 

 powers of the compasses by retouchmg then- needles; but the 

 effectual remedy, heat, seems to have been discovered, m con- 

 sequence of aA hypodiesis§ which has obtained the recent 

 honour of adopdon bv Dr. De Sanctis, widi htde variation, 

 except what results from his philosophic idea oUhc conversion 

 of the magnetic fuid into rtfned ethereal ice. 

 I am, gentlemen. 



Your very obedient servant, 



Francis Ellis. 



LXVI. Description of a new Priiiting Press. 

 To the Editors of the Philosophical Magazine and Journal. 



Gentlf-MEN, — Tii I s press may be used in common printing, 

 lithographic printing, and for various otlier purposes, and is 



verul years previous to his death, the oUlcst Menihcr or Father of the 



Royal Society. 



* Neitlier'thc approach of iec-inoiintains nor icc-iiiouiitauis, are m any 

 way mentioned. See Ellis's Voy!ij;e, page 2:21. 



■f Sec I-:ilis's Voyafie from page 220 to page 229. 



X Namely, fronipage 220 to page 22!J of his Voyage, entitled m the in- 

 dex " Some 'I'honghts on Magnetism." 



$ See Ellis's Voyage, page 22(!. 



equal 



