May 10. 1851.] 



NOTES AND QUERIES. 



371 



" Mais Azolin dans Rome 

 Sceut cliariner scs ennuis, 

 EUe eiit sans ce grand homme 

 Passe de tristes nuits ;" 

 adding : 



" Dans ce peu dc paroles Mr. de Coulanges [its 

 autlior] dit lieaucoup de elioses, et fait comprendre 

 I'intrigue du Cardinal avec la Reine." 



I can find no account of this Reverend Cardinal. 

 Who was he (if anybody), ami what is liis his- 

 tory ? And who was the author of these odd 

 memoirs of the Swedish Queen ? 



At page 228. of " I^otes and Queries " I see 

 mention of an English translation of Danish bal- 

 lads by Mr. Borrow. Is there any translation of 

 Noricegian ballads ? Many of them are verj' 

 beautiful and cliaracteristic, and well worthy of 

 an able rendering into our own language, if there 

 were any one to undert.ake it. There is also 

 much beauty in the Norwegian national music, 

 of which a pretty but limited collection, the 

 Norske Field- Melodier, arranged by Lindeman, 

 is published at Christlania. 



What is the best method of reaching Iceland ? 

 and what realhj good books have been published 

 on that country within the last twenty years ? 



AYlLLIAM E. C. NOUBSE. 



London, April 22. 1S51. 



THE KOTATION OF THE EARTH. 



Query, lias Mons. Foucault's pendulum experi- 

 ment been as yet clearly enunciated ? and do I 

 understand it aright, when I conceive it is intended 

 to show the existence of a certain uniform rotation 

 in azimuth of the horizon^ but difi'erent for different 

 latitudes ; which rotation, if made out to exist, is 

 acquired solely in virtue of the uniform diurnal 

 rotation (15° hourly) in right ascension of the 

 equator, identical in all latitudes. 



A pendulum, manifestly, can only be suspended 

 vertically, and can only vibrate in a vertical plane ; 

 and surely can only be conceived, in the course of 

 the experiment, to be referred to the horizon, that 

 great circle of the heavenly sphere to which all 

 vertical circles are referred. 



A spectator at the north pole has the pole of 

 the heavens coincident with his zenith ; and there, 

 all declination circles are also vertical circles ; and 

 there, the equator coincides with the horizon ; 

 whereby the whole effect of the rotation of the 

 earth there (15° hourly) may be conceived to be 

 given to the horizon : whilst, at the equator, the 

 horizon is perpendicular to the equator, which 

 tiierefore gives no such rotation at all to the hori- 

 zon. Simple inspection of a cele.-;tial globe will 

 illustrate this. Considering the matter thus, at 

 the polo the rotation of the horizon is 15° hourly, 

 and at the equator is 0, or nothing. But the sine 

 of the latitude (=90") at the pole is unity, or 1 ; 



and the sine of the latitude (=0°) at the equator 

 is 0. Therefore, at these two extremes, the e.\- 

 pression 15° x sin. lat. actually does give the amount 

 of hourlij apparent rotation of the horizon; namely, 

 15° at one place, and 0° at the other. Now, as I 

 understand the experiment, as given in the public 

 prints, it is asserted that the same expi-ession of 

 15° X sin. lat. will give the rotation of the horizon 

 in intermediate latitudes ; of which rotation I 

 subjoin a table calculated for the purpose. 



Now this is the point which, it should seem, ought 

 to be the business of experimenters to establish; 

 it being proposed, as we are informed, to swing, in 

 different latitude.s, freely suspended pendulums, 

 over horizontal dials, or circular tables, properly 

 graduated, similarly to the horizons of common 

 globes ; and to note the apparent variation of the 

 plane of oscilLation of the pendulums with respect 

 to the graduated dials ; these latter serving as re- 

 presentatives of the horizon. For the hypothesis 

 is (as I understand it), that the pendulums will 

 continue to swing each of them severally in one 

 invariable vertical plane fixed in free space, whilst 

 the horizontal dials beneath, by their rotation, will 

 slip away, as it were, and turn round in azimuth, 

 from under the planes of the pendulums. 



It should seem to be imperative on those who 

 wish to put this experiment to proof, to give .all 

 possible attention to the precautions suggested in 

 the excellent paper that appeared on the subject, 

 on Saturday, April 19, in the Literfirij Gazette, 

 copied also into the Morning Post of Monday t!ie 

 21st. To my mind, the experiment is beset with 

 practical dilHculties; but even should the matter 



