RANDOM NOTES

Dominion, Volume 32, Issue 157, 29 March 1939, Page 8

RANDOM NOTES

■■ 1 ■■■' 4* " i ll Sidelights On Current Events (By Kickshaws). Further offensive action is prophesied from Germany, but we are not told if this refers to the Press or the Military. A Japanese maid, it is stated, must observe most elaborate etiquette. The ritual about the treatment of china is almost incredible. * • • Modern monarchs of the oceans may rely on impressive oil engines, but M ellington’s marine drive has started for years with a chimney stoked on rubbish. « * • Russian meteorologists have made the genial suggestion that the weather all over the world is getting warmer. They point out that, not only are the glaciers retreating, but the area where the ground is frozen solid is shrinking toward the Poles. In case optimistic women rush out to purchase perpetual summer-wear, Kickshaws hastens to poiut out that this theory is not yet proven. Meteorologists are very chary about basing long-term prognostications on data collected over a very short time. A period of 100 years is a very short time when we are dealing with weather changes involving perhaps 10,000 years, or even more. Vagaries of 30 years or so are insufficient for a basis on which to assume that the changes noted will persist for a long time. All manner of curious weather vagaries have been noted, but so far no correlation has been found that explains what will occur by means of a formula based on the past.

When one looks at the climate of the world with an eye that regards 10,000 years as a short time, it becomes apparent that some remarkable changes of climate have occurred. Experts believe that we are living in what is best styled a post-glacial period. What is usually termed the fourth ice age. took place between 50,000 B.C. and 25.000 B.C. The permanent snowline at that time descended the mountains to an average height in Europe of 3500 feet. Folk who lived during this ice age could note no change in conditions, because only four generations span a period of 100 years. There would have been little noticeable change if scientific records had been kept over a period of 1000 years. Moreover, minor changes involving a few centuries might have occurred, due to various confusing reasons not connected with the general trend of climate. It is probable that an ice age comes and goes, not as a beautiful curve of growth and decay, but as the average of a whole collection of minor changes which mask the real trend.

But one regards the climate of the world with an eye that sees, not in periods of 10,900 years, but in a period of Half a million years, it becomes apparent that the last glacial period was only one of several. The usual number suggested is four, but there may have been others. Each was followed by warmer periods. In some cases the interval was so warm, places not considered hot today were actually tropical. Indeed, there is a suggestion that, as recently as 3000 years ago, New Zealand was enjoying an almost tropical climate. In view of the fact that folk in the South Island are always complaining that they are left out in the cold, we would hasten to point out that this genial warmth was also shared by that part of New Zealand. For some reason that has never been explained, a sharp drop in temperature occurred all over the world between 1000 B.C. and 500 8.C., giving us our present; climates. There is reason, to believe that these climatic changes took place all over the world and were not exclusive to Europe.

Just at the moment, we are recovering from the sharp setback that the more genial climates of the world received between B.C. 1000 and 500, when, for no known reason, the temperatures fell abruptly. If that be the case, it would not be reasonable to assume that the present recovery will continue indefinitely as a part of the major movement away from the last ice age. flow long the recovery will last cannot be calculated bj' continuing the curve of rising temperatures into the future. We cannot assume that no further factors will be introduced. All that can be assumed at the moment is that our climate is affected by a rather cold in-ter-glacial epoch. Nevertheless, there are reasonable grounds to assume that climates are tending to become warmer. In the future, therefore, temperatures should rise. It is probable that rainfall will increase at the same time. Perhaps in 10,000 years it will be possible to observe changes of sufficient magnitude to bo able to state more definitely where the climate is going.

Efforts to probe into the future trends of climate are futile till it can be established what has caused’ climatic changes in the past. It has been established meanwhile, that there is a tendency for the ice of the world to melt and for climates to get warmer. The worst that could happen would be for the ice caps at the Poles to melt away completely. This would raise the level of the oceans by about 200 feet. The city of 'Wellington would be wijied out, as, indeed, would be most of the cities of the world and huge areas of agricultural lands. Geologists can give us information regarding past climates. Astronomers suggest that changes iu climate are due to eccentricities in the earth's orbit. It may be, also, that we traverse colder spots in space from time to time. Though the woi'ld repeats its journey round the sun over and over again, it never traverses the same spot of space twice. Moreover, when eccentricity is at its maxiiuum, the world is 5,000.000 miles nearer the sun than at present. Another theory suggests that the sun itself is a variable star and throws out a varying amount of energy. A variation of onlyhalf a magnitude would be sufficient to account for all climatic vagaries of the past million years.

Regarding the magnification of a telescope discussed in this column recently, the facts were obtained from an optician of repute. “L.C.,” another optician, however, writes: —

“With all due respect to your sources of knowledge in your article re the telescope, you appear to be misinformed. The magnification of a telescope is given by:—Focal length of objective over focal length of eyepiece. Focal length of a lens equals 100 over power eras. In this instance, focal length of objective equals 100 over 1.75 cms. equals 57 cms.; focal length of eyepiece equals 100 over 12.5 cms. equals 8 cms. Therefore magnification equals 57 over 8 equals 7 (approx.). Since your correspondent requires a higher magnification. he should either: (1) Increase power of eyepiece, i.e„ minus 15 or minus 18. etc.: (2) decrease power of objective, i.e., plus 1.5 or plus 1.00. If he wanted to shorten focal length, using a plus 4 as objective, he also must increase the power of his eyepiece to minus 40, approx. Personally’, I would advise him to reduce the power of the objective slightly.”