In America it has been discovered that the canker-worm, which infests fruit-trees to a mischievous extent, can be effectually checked and destroyed by smearing the stem and branches with printers' ink. It is interesting to know that there are two ways in which printers' ink can be made use of for the suppression of pests. And in France experience has proved that the Phylloxera can be destroyed by planting red maize between the rows of vines. The insects quit the vines and attack the maize-roots.
Meteorologists are well aware of the fact, that as a rule the barometer rises and falls twice within the twenty-four hours. Wherever observations are made, this movement is seen; and attempts have been made to refer it to the influence of tides in the air. But what causes the aërial tides? Some observers say magnetism, others say heat and differences of temperature. Mr Blanford, meteorological reporter to the government of India, has studied the subject; and in a communication to the Asiatic Society of Bengal, he remarks: 'It appears in a high degree probable that a great part of the diurnal irregularity of the barometric tides is due to the transfer of air from land to sea, and vice versâ, and to a similar transfer which may be proved to take place between the plains and the mountains. But the phenomenon is very complex, and much study and labour are yet required to unravel its elements, consisting as they do partly of elastic and reactionary pressure, partly of dynamic pressure, and partly of variations in the static pressure of the atmosphere. Till this shall have been done, and it shall be found, after all, that heat and its effects are insufficient to explain the phenomenon, it seems premature to resort to magnetic and electrical phenomena for the explanation of the barometric tides.'
Amateur meteorologists would do well to remember that the trustworthiness of the anemometer as a measurer of the force of the wind is seriously affected by the presence of trees; even a single tree will exert a disturbing influence. For wind-observations, the more open the space the better. We hear that the Meteorological Office is about to place at a high elevation an anemometer which will indicate its work to the observer below by telegraph. In the study of the weather, it would often be of advantage to know the rate and force of the wind on the top of St Paul's or Ben Lomond.
It had been noticed that ozone was developed by the spray of water when under pressure; Signor Bellucci was thereby induced to make observations at the Falls of Terni 'to ascertain if ozone was produced by the natural pulverisation of the water, especially as he had often noticed there the characteristic odour of ozone.' The tests employed completely demonstrated the presence of ozone, and that the quantity varied with the volume of water rushing over the Falls. From this result Signor Bellucci concludes that wherever water is converted into powder or spray, whether by a cascade, a torrent, or by the rolling of waves, there ozone is produced. 'It is noteworthy that the air over the surface of the ocean is richer in ozone than that collected on land. Hence the production of ozone may be due to the electrical state induced by the friction of the minute drops of water against one another, which is increased by the mineral matter suspended or even dissolved in the water.'
Land flooded by the sea generally remains barren many years. The Journal of the Chemical Society gives a German chemist's explanation of the reason why. The land is charged with too large a proportion of chlorine salts; it has a tendency to remain damp; and there is a formation of ferrous sulphate, which, as is known, exerts a very prejudicial influence on plant-growth. Land when brought into this condition by an inflow of the sea, should be drained as quickly as possible, and sown with grass or clover and allowed to rest. Experience shews that it recovers its fertility sooner if treated in this way, than when cultivated all the year round as arable land.
In the course of a lecture on the Motion of Waves in Air and Water, by Professor Guthrie, a light, hollow india-rubber ball was floated on water, and a vibrating tuning-fork was held near it. The ball moved towards and followed the fork. Why? Some people might say that the fork attracted the ball; but the lecturer decided that attraction had nothing to do with it. Each oscillation of a wave is followed by a reflection: in this case, the reflection pushed the farther side of the ball; from which the conclusion was drawn 'that there is no such thing as attraction—that the apparent pull will be found to be a push from the opposite direction. The approach,' said Professor Guthrie, 'need not necessarily be called attraction, and it is better in all cases to substitute the word approach, which is a fact, for attraction, which is a theory.'
Mr Siemens' paper on the Bathometer, which we noticed some months ago, is now published in the Philosophical Transactions. Objections have been made to the instrument as an indicator of the depth of the sea, because the sea-level is disturbed by the attraction of large masses of land. Mr Siemens answers that he is aware of the objection; that the bathometer is not expected to do more than indicate comparatively small variations in total terrestrial attraction, which the hydrographer or navigator using the instrument will have to interpret according to the circumstances of the case. If the zero-point of the instrument varies with the latitude, or in consequence of special geological causes, we must bear in mind that these causes are of a permanent character, and that when an ocean has been once surveyed by means of the bathometer, the special local conditions become observed facts, and would thus serve to increase the value of the bathometer as an instrument for measuring the depth of the sea without the use of the sounding-line.
At a meeting held at Salem, Massachusetts, a lecture on 'Visible Speech' was delivered by Professor Graham Bell, who, by means of the drum in a human ear cut from a dead subject, has succeeded in producing a phonautograph. The ear is placed in the end of an ordinary speaking-trumpet; on speaking into the trumpet the drum is set in motion; this moves the style; the style traces the effect on a plate of smoked glass; and by means of a camera the curves and lines can be exhibited to a large number of spectators. The five vowels make five different curves; and according to Mr Bell, there is no such thing as a sound or tone pure and simple, but each is a composite of a number of tones; and the wavelets by which these are produced can also be shewn on a screen. Tables of the various symbols have been drawn up, and found useful for educational purposes, as was demonstrated by a young deaf and dumb pupil from the Boston Institution, who interpreted the symbols at sight.
Professor Bell has improved the method devised by his father, formerly of University College, London, for rendering speech visible; and as is well known, membranes have long been used for experiments in acoustics. Some of our readers may remember the experiments of Mr W. H. Barlow, F.R.S., described in his paper 'On the Pneumatic Action which accompanies the Articulation of the Human Voice,' read two years ago at the Royal Society, and published in vol. 22 of their Proceedings. And within the past few weeks we learn that the telephone has been so far improved that an account of a public meeting was talked into one end of a wire and was distinctly heard and understood at a distance of eighteen miles.