CONTENTS, Vil 
ad Pag 
Mf. Tuomas Gruss on Iniprovements in the Optical Details of Reflecting 
Telescopes and Equatoreal Instruments «+...4:+-s265 SaetU avmaonadsapate oothas erases 8 
M: 1’Assé Moteno on a Method of determining whether the Luminiferous 
Vibrations are Parallel or Perpendicular to the Plane of Polarization ......... 9 
Evectricity, MAGNETISM. 
Captain BLakety’s Mathematical Investigation of the Proportion between the 
Length required for an Electric Telegraph Cable and its Specific Gravity ... 11 
Rev. Professor Cauuan on the Electro-dynamic Induction Machine ...:..:. sue 121 
Mr. Joun Hartnup on Controlling - Movements of ordinary Clocks by 
Galvanic Currents .:...:....s-4. wag ok Dedot Manan stiaataspa Res casa vidoes cus aavaoiooanen's 13 
Major-General Sasine on the Amount and Frequency of the Magnetic Dis- 
turbances and of the Aurora at Point Barrow; on the Shores of the PolarSea 14 
Professor W. B. Rocrrs’s Brief Account of the Construction and Effects of a 
very powerful Induction Apparatus, devised by Mr. E. 8S. Ritchie, of Boston, 
United States co.ccijc.i.s ess cosecase aca cadgescaaxe pegeeaeantss “estos Scoscccsssevecss . 15 
M. Louis Sorer’s Researches on the Correlation of Dynamic Hlectricity and 
the other Physical Forces .............sce0ee-seeee Becicsstcaatanssboasestataseeansstetys 16 
Mr. G. Jounstone Stoney’s Description of an MeO a. of Grove’ s 
PREEUCEY -stetirestrccsetsiageaicrcesans stctesseesste npigdidooceadnt Sas deecesictteTesitisse ss. 20 
Professor W. Tomson on Mr. Whitehouse’s Relay ea ee Coils i 1) ee 
BCUION Bil HUGEE CMCUNL 2) ce522ttszesc.cisecs tb ecddaccasbeesassgecasteecahdeasetaaddtdane 21 
—_— on the Ritects - Induction in long Submarine Eines oF ow 
Telegraph csscessccesetsstscaesseasssceesss Sectesieds sees Miisshtsassiisesdasstucdacezete ta BE 
Mr. J. Dktmmownn’s Outline of a Theory 4 pl ee and Iiaiceees a 
homena Of the Globe ..is.s.6scc:...ccesesccseesseassaasasecetssesas apecevercees ssesssss 22 
Mr. W. RuNbeEti’s Magnetic Experimetits made on board the ‘ Great Eastern’ 
Steamer. (Communicated by Admiral FITzZR0y.).....5...ssceeeees ssaneGbensudete 22 
Sounp. 
Mr. M. Donovan on a singular Acoustic Phenomenon ...........0006 saanekeenene 22 
Professor G. G. Stoxes on the Effect of Wind on the Intensity of Sound ...... 22 
ASTRONOMY. 
Cavaliere O. F. Mosorri on the Distribution of the Orbits of the Comets i in 
Space MESA LONE RTSS SSS aE aes tse cee eee ecccecdae essa tes dessentesameeee ee res seedne2eivassise 93 
Mf. M: Donovan on a Moveable Horizontal Sundial; which shows correct 
Solar Tiiie within a Fraction of A Minute ii.sscscsiccscciseccsstcccssecsccscctisnes 24 
Mr. C. THomson’s Tables to simplify and feria? more general the Method of 
finding the Time; by observing Circumpolar Stars in the same Vertical: (Com- 
municated by Sir W. Ri HaMILTON:) ...i.:..55 suésege) se ebis ssi0sdasssseeeciasstiess = 94 
Professor Hennessy on the Direction of Gravity at thé Barth's Surface:...i::. 24 
—_———S=_ éh the Solidification of Fluids by Pressure:s:.isiecssseses:, 25 
Professor Loomis on the relative Accuracy of cae Gurerent Methods of deter- 
fining Geographical Longitud® tiz.sassiseczscacescastaatsscsaateea cos sasesateascats 25 
Mfr. J: J: Murpuy of 4 Proposal for the Establishment of a Uniform Reckon- 
ing of Time in connexion with the Telegraph .iisscicsssssccsissseecsteesesascsecees 26 
Mi. J: Nasmyrx on some Phefiomena in connexioh with Molten Substaiices... 26 
