Cosgrave spoke of it as "seeing our renaissance in action," and the Minister of Education said he looked upon it as a necessary step in the carrying through of what was, from the national point of view, a great reform. It was not necessary to dwell on the importance of the college as a factor in the national life, but it would, he added, be impossible to exaggerate the influence of the school. The Free State policy of compulsory Irish for schools is the most striking example in modern times of political influence in education. It is not surprising, therefore, that it evolves strong criticism. Captain Redmond objects to it for three reasons: (1) compulsion infringed personal liberty; Ireland did not gain freedom for one section to tyrannize over another; (2) compulsion defeated itself by rendering the study of the language unpopular; and (3) the method of its application was working ruinous mischief in the whole educational system.

IF

Teaching

of Art.

F the Free State does not prosper, it is not for want of the advice of continental experts. The Germans are running the new electricity scheme on the Shannon, the Belgians the sugar industry in Carlow, and the French the cleansing of the Dublin streets. The French are also to be called in to advise on the teaching of art. For a new departmental committee has been appointed to inquire into the organization and work of the Dublin Metropolitan School of Art and into the teaching of art generally in secondary and technical schools. The committee will consist of seven members-Mr. Dermod O'Brien, President of the Royal Hibernian Academy;

Mr. T. Bodkin, the well-known art critic; two representatives of the Department of Education; and three Frenchmen-M. Druot, M. Rambosson, and M. Brunot, all from Paris. The committee is to give special attention to the training of specialized art teachers for the schools, and will also consider how art can be best linked up with native industries. The work of the committee is expected to occupy it for several weeks.

THE Dublin City Commissioners, whose work in reof the Irish capital has met with general and well-merited placing the old Dublin Corporation in the control

The Health of Dublin School Children.

approval, have adopted a new scheme. for the medical inspection of children in the Dublin schools. The scheme contemplates the appointment of two permanent whole-time assistant medical officers of health to act as school medical officer and assistant school medical officer respectively, each to be assisted by two specially trained nurses. The work is to be co-ordinated with the maternity and child welfare schemes, in order to secure a uniform system of treatment. It will begin with a census of the health of all the school children of Dublin, an arduous task, as every school must be visited and every child examined. A record will be made and kept of every child's physical condition, with the object, by advice and prevention, of preserving the health of the children. Beyond question this inspection will effect striking improvement in child-health, and will react for good on education; if once the Dublin slums could be cleared away and replaced by modern sanitary dwellings. the improvement would be extraordinary.

A

TOTAL eclipse of the sun is an event which from the remotest times has aroused widespread interest and wonder. When mankind was ignorant of the cause of the phenomenon it must have been unexpected and terrifying: now, when the time of an eclipse can be calculated years beforehand to within a fraction of a minute, we are no longer filled with fear. We look forward to it eagerly as perhaps the most marvellous spectacle in Nature and a unique opportunity for the gaining of scientific knowledge.

It is well known that a solar eclipse is caused by the moon passing between the observer and the sun. The nature of the three different kinds of solar eclipses and the conditions which give rise to them are less widely understood. To make the matter clear, we must remind our readers that the earth moves round the sun in a path which is not a circle, but an oval or ellipse departing but slightly from a circle. The result is that throughout the year the distance from the earth to the sun varies through a small amount; and this of course means that the apparent size of the sun must also vary throughout the year. We are nearest to the sun in January and furthest from it in July. The apparent size of the sun is best stated as the angle which its diameter appears to subtend at the observer's eye. Early in January this has a value of about " 32 minutes of arc"; at the beginning of July it is about " 31 minutes." In the same manner the moon moving round the earth in an ellipse, varies during each month from about “32 to about 29 mirutes." Thus, according to the positions of the earth and the moon-more particularly the moon-in their orbits, the moon, when seen centrally against the disc of the sun, may or may not appear large enough to cover up the whole of the sun. If the moon covers the whole of the photosphere (the bright surface which we ordinarily see and which we call 'the sun "), then a total eclipse results. If a ring of the photosphere appears round the centrally placed moon the eclipse is an annular one. If the moon appears to pass across only a part of the sun's disc, not centrally, the eclipse is a partial one. The facts may be expressed in another way in an annular eclipse, the moon is so far away from the earth that its shadow does not reach the earth. The diagram shows the sun, and also the moon with its complete shadow or umbra (lined) and

there is about one total solar eclipse every two years. But because the width of the track of the moon's shadow on the earth cannot be greater than about 170 miles, (and it is usually very much narrower than this), in any given place the earth a total eclipse is an extremely rare event. Thus the last total eclipse visible in the British Isles was in 1724, while the next after the eclipse of this year will not be till 1999. On the average there are about three total eclipses in a thousand years at any given station.

on

The predicting of eclipses does not involve a knowledge of the principles of modern astronomy, for eclipses recur at a regular interval called the Saros, which was known to the Chaldeans three thousand years ago. This period is eighteen years eleven and one-third days. Thus the track is brought back to the same part of the world after fiftyfour years. But there is a constant gradual change in the conditions of the eclipse, and even after fifty-four years the shadow does not follow exactly the same path.

It has been stated that a total solar eclipse gives a unique opportunity for the advance of scientific knowledge, This is because it is only while the photosphere is completely covered by the moon that the sun's corona can be observed. As the moon advances from the western or righthand edge of the sun, covering more and more of the sun's disc, the sky becomes darker, and, as totality approaches, the brightest stars and planets become visible. The shadow of the moon rushes along the surface of the earth at a velocity never less than 1,000 miles an hour, and often very much greater (in this year's eclipse the velocity of the shadow across England will be over 5,000 miles an hour) and when it reaches the spot where the observer is situated the photosphere becomes completely covered. Round the black surface of the moon it is then possible to see the sun's chromosphere, a glowing red atmosphere of gases of a depth of about 10,000 miles. Growing out from this atmosphere there are seen a number of flame-like objects, the prominences, composed mostly of glowing hydrogen and extending sometimes to a distance hundreds of thousands of miles beyond the rim of the sun. Except during totality, the chromosphere and the prominences cannot ordinarily be observed with the naked eye or with a telescope, though whenever the sun is shining they can be

SUN

MOON

EARTH

its partial shadow or penumbra (dotted). The earth is drawn in two positions, as a complete circle relatively near to the moon, and as a broken circle further away from the moon. When the moon's shadow reaches the earth a total eclipse is seen over a narrow belt as at T. When the moon's shadow fails to reach the earth, owing to the greater distance apart of the two bodies, an annular eclipse is seen as at A. In either case the eclipse will appear as a partial one to observers over a wide area on each side of the central belt. In the diagram, the bodies themselves, the dimensions of the eclipse, and the distances, are not drawn to scale.

If the orbit of the moon and that of the earth were in the same plane, a solar eclipse would occur once a month, at the time of new moon. Actually there are never less than two and never more than five solar eclipses in a year. A large number of people believe that a total solar eclipse is a rare event. This is by no means true, for on the average

observed by means of a spectroscope used in conjunction with a telescope. Outside the chromosphere and prominences, so long as the sun is totally eclipsed, there can be seen the corona, a moderately bright whitish glow extending to a distance sometimes greater than the apparent diameter of the sun. This remarkable appendage of the sun has never been observed except during totality: the illumination of our atmosphere is too bright for the corona to beseen at any other time. It varies in form at different eclipses, the form depending on the state of the sun with respect to the eleven-year sun-spot cycle. At sun-spot minimum, long equatorial streamers are observed, while at maximum the corona is less extensive, but more uniformly distributed round the solar disc. The latter type may be expected at the June eclipse as we are now approaching a time of sun-spot maximum. Our knowledge of the corona is very limited. Its structure and composition and (Continued on page 314)

even its nature are very little understood; and it is in the investigation of this part of the sun that the chief scientific importance of total eclipse observations is found.

Among total eclipses, the one which visits England this year cannot be described as a favourable one. The greatest duration of totality in any eclipse under the most favourable conditions is just less than eight minutes; about three minutes is a more usual time. In the eclipse of June 29, totality is predicted to last for only about twenty-four seconds. Before and after these precious few seconds the corona, the chromosphere and the prominences will be quite invisible. The eclipse begins at about 5.30 a.m. summer time; totality occurs at about 6.25, and the sun will then be only about twelve degrees above the horizon— three degrees lower than its midday altitude at London in midwinter. The eclipse will be over by about 7.20. Nevertheless, if observers are so fortunate as to have a cloudless sky they should see the chromosphere, the corona, and the promin nces. The sun at this date will be in the constellation of Gemini. There will be two third magnitude stars just above the sun on the right and one not far distant on the left. Aldebaran will be nearly due east at an altitude of about 25°, Capella further round to the north-east at an altitude of 40°. Jupiter will be due south at about 36° altitude, but the other bright planets will be below the horizon. The aspect of the sky will be the same as it is at about six o'clock in the evening at the end of December.

The accompanying map shows the path of the moon's shadow as it passes from west to east across the surface of

part of Wales and northern England. The shadow will be about 30 miles wide. Places very near the central line are Criccieth, Southport, Settle, and the Hartlepools; Sunderland and Fleetwood are very close to the northern limit of totality; Saltburn and Liverpool are just inside the southern limit. Expert astronomers will have decided beforehand how to employ their cameras and spectroscopes so that not a second of totality shall be wasted.

What advice can we give to observers who cannot make helpful scientific observations? They must see the eclipse; and there is a great deal to see in a very short time. One sometimes hears people say, "Well, even if it isn't total here, it will be very nearly so." This implies that they think that an eclipse which is very nearly total is almost as fine a sight as one which is total. This is quite wrong. Absolute totality is essential in order to get any view of those parts of the sun which are not seen at ordinary times. The strange darkening of the sky and the visibility of some stars in an annular or a large partial eclipse are interesting; but the total eclipse is a very much more wonderful spectacle. But if the sky is clear, it is not necessary to be exactly on the central line in order to get a satisfactory view of the eclipse. Five miles or so on either side of the central line makes practically no difference in the duration of totality; and at Liverpool and Durham which are much nearer to the edge of the shadow belt than to the centre, the total phase is predicted to last eighteen seconds and twelve seconds respectively.

The Ordnance Survey Office, Southampton, has pub(Continued on page 316)