THE TRANSIT OF VENUS.

Clutha Leader, Volume I, Issue 17, 29 October 1874, Page 3

THE TRANSIT OF VENUS.

In reply to several enquiries, we may mention that the much*talked of transit of Venus will occur on Wednesday, 9th December. Tbe following particulars are from Mills, Dick sod Co.'s Almanac:— . -. , mean B. m. p.m. tlmo. ExternaUontaetatincT^ - {JiggS" nd Internal contact at Ingres. , {) gj; g^£ d Least distance of ceotrea 18*6:7 f* Internal contact at Egress { j ££, jf^jg; d Extemalcontaetatßgre^ { g .gg »g™ d For direct (First external euntact 50« towards E imaee ADifie } First internal contact 44° towards v. from North } Last internal contact 14° towards W . role of (.Last external contacts;*) 0 towards W The following notes are supplied by Mr Ellervi of Melbourne :— . Observations of the transit of Venus across the sun's disc will be principally confined to the determination of the exact time at .which the planet's disc enters upon that of the sun ; and those particular instants when the outer edge of the planpt is in precise coincidence with the sun's edg-e, call d internal cootacts, will be taken. These contacts occur when Venus first shows as a full rounds disc, on entering 1 in the sun's disc, and again while she still shows around disc just • before egress. Such opera- | tions require the use of good telescopes; well mounted, with apertures of not less i than 3in. or .2 Jin ; they also require ! tbe use of a good clock or chronometer, i and the exact local mean time or sideral ! time. .For simply . viewing the.pbe- 1 nnmenon very simple apparatus will be fufficient.; To good eyes protected by deep colored or smoked glass, Vemis will be visible after she is well on the sun's oisc. Any ordinary telescqpps, and even binocular, opera, or field glasses, will give . a better view ; but whatever telescope is used, great care is necessary to protect the eye from the intense glare and heat concentrated at the eye aperture, and if proper sunshades be ; not provided with the telescopes, they must be improvised before attempting to look at the sun, for many have lost or injured their eyesight by not attending to this most necessary precaution. Deeply colored glass, especially, a piece of deep red, and a piece of deep green or blue together, will be found very safe and pleasant ; a piece of blue or green, or deep neutral tint, will also do ricely. If , none of these can be obtained,, the old fashioned smoked glass will firm an excellent substitute. The proper method of making this is : — Obtain two strips of thin clear glass, say Sin long by Tin broad (the glass aold for microscopic slides is tlie best) ; around the margin of one. of the surfaces, paste a slip of thick writing paper about the eighth of an inch broad, and smoke this surface •■by holding it over ah' -."heed candle with a long wick, or a small kerosene flame (without chimney) taking care to warm the glass gradually fit -first, or it will crack. The proper density of the, blackening can be got "after a few trials. After the right kind of .smoked surface has been obtained, the second glass can be fastened ,ov*-r it j .the strips of paper will keep it from coming in ; contact ; by pasting a strip of thin paper over the ; edges so as to hold the two glasses together, a dark shade fop observing the sun is formed, which will last any length of time." ■ aimmmmmmimmtmitmummnfmmmam ' -