HALLEY’S COMET.

Manawatu Herald, Volume XXXII, Issue 840, 17 May 1910, Page 3

HALLEY’S COMET.

Tlie well-known meteorologist, Mr Ci<-me:it Wragge, wrote prior to his < 1 uj;f; tine from Auckland for Tasmania Use fol'nwing letter ; —•* Referring to the canids passage through the cum-i’s tail, calculations show that tiic earth should enter the upper pari, .of the tail of Halley's emiiel ,a !..-,e p.m. on May iplh, ami go therelrom at p.m. (New Zealand standard time;. Watch sun and star eilects now. People must not ire alraicl. Nothing very sei ions is likely to happen, for the Ini: is so thin and tenuous that this earth will tackle it like an elephant running amok in a spider's wb. Even assuming that the cyanogen gas mingles with our atmosphere, well, people with highly-strung nerves and weakish lungs may be inclined to puff and sneeze a bit or they may not. At any rale, let me advise nervous people to go to bed lor an hour at the time named, and shut the windows and paste brown paper over the c:e-vices, and they should emerge safe ami sound, as did Xoah and his family from the alleged ark, and ii the tail contains hydrogen, well, it might ire well !ur a select few, including Sir Joseph Weird and the Hon- R. McKenzie, and not forgetting the Hon. Geo. Eowlds and yourself, sir, to shut themselves up in an asbestos chamber during the passage, and on coming out they

can then set to work to frame new laws, build new railways for the benefit of the surviving few, not insisting tiiat the remaining pubs should dose at 10 o’clock. Never mind, all will be well, and il we nave to go, we'll bold an ethereal banquet on the astral plane, to commemorate the event. May God bless all your readers, and shield them from ‘ Dadion,’ for such, I understand, is the comet’s real name. —Yours till the transit, Clement. Wragge,”

Opinions as to tiie length of the tail of Halley's come:, vary considerably. Writing to the Sydney Daily Telegraph on April. 22nd, Mr I). 11. Beattie, of West Point Observaloiy, said :—"lt is not at all likely Horn present appearances that the tail will be more than one million miles 111 length at the lime of passing the earth on May 19U1, so that theie is no danger of its coming into contact with it. But what is that danger ? It has been said that the muiior composing a comet could oe rolled into a small parcel, but this is an exaggeration. A few figures will prove that if the tali of the comet extended to the earth, and it would not be unduly large to do so, it would be possible to assign toil a maximum weight, exclusive of the head or nucleus, of 400 million tons, and this weight could not he much exceeded ; and even then, owing to its enormous volume, its mean density would be 560 thousand times less than that of earth's atmosphere at sea level, and that would be equivalent to the atmospheric density at a height ol sixty miles above the surface of the earth. As, however, the extiemily ol 1 lie tail is much less dense than the mean, n is not probable that any portion of the comet could penetrate within ioo miles of the earth's surface, the atmosphere acting as a heavy armour-plate does to a. bailie-ship,”

We have received ihe following interesting loiter naan MrFrcdk.R. Field, of Aramoho, Wanganui, in reference b> Haller’s Comet: — " The Herald, mi Momlay evening, gives nnl.-s upon the above bv Father Allen, ot Meanee Observatory. When he speaks ol the comet’s head being 79,000 miles timing h he, of course, in eludes he whole m Lhecuuicl, not merely the nucleus, for the latter A, apparemlv, mil}’ about the size ot the earth. Though there is no record ot a comet’s nucleus having been visible whilst passing in front of the sun, it is highly probable that such a sight may be witnessed on this occasion—that the nucleus will be seen as a nebulous round Mutch, in diameter about onotwenlicth that of the sun, travelling aeioss almost the middle of the sun iioin west to east. Friday morning was the first morning we have had tor some time clear enough to observe the comet ; but even then the civ cannot have been so clear here as at Meanee, for though the measurements ot the tail allowed it long enough to reach the earth, there did not appear to be as much as 3,000,000 miles to spare. As viewed from the earth, the tail appears to be about a,c00,000 miles wide at the part where the earth will pass through. This means that whilst we are in the tail we shall have it extending for about a million miles north and south ul us, lor we puss very nearly through the middle ol it, but it by no means represents the length ot the earth's journey from front to back of the comet’s tail. The time occupied in passing through it will undoubtedly be much more than fourteen hours. It is reasonable to expect that the earth will pass through the first, and lightest, jet (so to speak) of the tail at about 8 p.m. on Thursday next, through another such jet at about the same hour or earlier on Friday, and enter the main ami densest portion ot the tail about Saturday afternoon, not to emerge from it entirely till fully two days later. Thus, there should be some part of the comet’s : tail between us and the sun lor at least four days after the trausit of the nucleus on Thursday afternoon. Meteorological observations must be affected, but to what extern, and in what direction, cannot be predicted. The brilliancy and colour of the sun may be expected to change. Whilst passing through the tail at night we shall

probably notice some twilight effect, more particularly before sunrise on Sunday. The presence of the moon will render this less noticeable earlier in the night. From now on till Thursday, the tail, seen before sunrise, will appear both to lengthen and to increase its spread. Very little, if any, of it will be visible just after sunset on Thursday, and, if seen clearly enough, will present the extraordinary spectacle of a comet with the outer end of its tail turned back towards the sun. From Friday onwards the spread of the tail will appear to grow less, its outline for a time appearing curved- The length will seem to increase lor a time, and to be at its greatest probably on the evenings of the 24th and 25th. The old notion that we shall experience increased temperature may prove correct. But I should expect instead a slight general fall in the thermometer for the first two days after the transit, then a slow rise to normal. It the solar radiant theory be sound, the barometer may be expected no rise several times above normal, indicating the highest pressure about Sunday morning. But, it the theory be incorrect, there will probably be an unusual fall each time we enter a section of the tail. Strong winds may be looked for. In such ways the barometer and thermometer may help to settle various questions that are in doubt, but the objection to them is that the observations are not amenable to shock. Electric and magnetic disturbances directly due to the comet are not so likely to be detected. But the most important investigation to be made, I think, whilst the comet is passing us, lies iu the direction of refraction. Observations taken to the sun before and during the transit of the nucleus, and to the sun and stars periodically for several days afterwards, would probably reveal to us some ot the mysteries, not only of comets, but also of the circumsolar medium in which our planets move. We now have the unique opportunity of making some comparisons between the densities of the comet’s gases and the surrounding medium. If, as is generally believed, the comet’s tail be composed of gases iu vacue, then directly the head begins to intervene between us and the sun the western side of the sun must become distorted. When the comet’s head, occupying about bait the sun’s diameter, reaches the opposite or western side of the smi, that side also must appear distorted, perhaps visibly so. This suggested distortion, which would gradually spread over the whole sun and then make it to appear to move irregularly and slightly out of its proper course, cannot with our present knowledge, be exactly foretold, because it must depend upon conditions which those distortions alone can tell us. The observations taken on Saturday and Sunday would probably show the irregularity at its greatest, aud if the conditions be as generally surmised, should then represent the sun considerably in advance ot its calculated position. On the other baud, if the comet’s tail lie dependent upon gravitation, those observations will show the sun somewhat behind that positiou. In any case observations taken upon the lines I suggest would in all probability throw a flood of light upon much that is now beyond our kin. Series of photographs ol the sun taken during the transit of the comet’s bead on Thursday afternoon might fairly be expected to show a sight that has never been seen be 10re, and so yield scientific data of the greatest value. So far a 1 i know the observations retired to have never been attempted before, and are uot contemplated by astronomers at the present time. Such an opportunity as the present is net to be lost ; for it cannot be expected to occur again within the next few centuries. As for the transit of the comet’s head, we, on this side of the world, shall have it all to ourselves. I wonder that the leading astronomical societies have uot made more preparation for it.

Nkw York, May 18. Mr Forbes (vice-president of the Aero Club of America) and Mr C. Yales, who attempted to establish a long-distance balloon record, but who were subsequently discovered, wounded and unconscious, near Glasgow, Kentucky (the pair had started from Ouiucy, Illinois),are recovering. They reached an altitude of 2000 ft. They state that Halley’s comet was a gorgeous sight, there being an absence of terrestrial dust. The comet has a brilliant head and a long veil-like phosphorescent tail. Photographs of the visitor were taken. The aeronauts suffered from want 01 oxygen. The linal fall was from a height of 300 ft. Their lives were saved by rubber air mattresses in the bottom of the basket of the balloon.