Oxford Museum, has been received there, together with his books and notes on Arachnida, and placed in the charge of the Hope Professor of Zoology.

In the present state of our food supply our deficiencies in combating insect and other pests which attack our crops are brought home to us, and it behoves us to use our best endeavours to overcome them. I have lately heard a great deal about the strict inspection of orchards and crops in Australia, and how any trace of blight or other pest has immediately to be stamped out by the farmer by the destruction of the tree or orchard, if no other means are successful. I fear that not many of our orchards would be left standing were this vigorous system adopted here, as they are usually left more or less to themselves, and but little is done in the way of pruning and general treatment. Nevertheless we often get very large crops, as last year. The gooseberry mildew seems to have somewhat improved; but the recently imported potato-wart disease has spread. Potato spraying for the old potato disease has been intensively carried out; and the balance of evidence seems to be in favour of this practice, though personally I have had the best crop I have had for years without any spraying at all. The effects of spraying are somewhat transitory, so that the process should be repeated two or three times during growth. Some interesting experiments conducted for 30 years have proved that some fermentation organisms (doubtless successive generations) can be kept alive artificially for that period by the employment of a solution of cane-sugar and other nutrient media in a Pasteur flask. Higher organisms in the shape of caterpillars, chiefly those of the winter moth (Cheimatobia brumata), have done harm to apple and other trees in some districts by stripping them of their leaves. This is usually guarded against by a greased band round the trunk to stop the ascent of the wingless female moth when egg-laying. Some Scotch

experiments on manuring have shewn the yield of oats when fully manured to be about a third more than on unmanured plots, and about a third more also than the average yield in Scotland. As regards artificial manures, this country was chiefly dependent on Germany for its supplies of potash; but a process has now been discovered by which sufficient can be obtained for our needs. The manufacture of other artificial manures has undergone great development ince the war in response to the closing of the usual channels of our supplies. Many other substitutes for substances formerly used for different manufactures have been found. Thus bark is used for making paper, willow herb (Epilobium hirsutum) and typha instead of jute. These are in Germany, where jute is, I presume, unobtainable. Rhubarb leaves were recently recommended as a vegetable; but questions have arisen about their wholesomeness; and we may perhaps wait until compelled by necessity, as there are many wild plants which are more suitable for food. Ragwort has lately been put forward as a poisonous plant to cattle, though its effects are slow; but it is an exceedingly abundant weed in many semi-waste pastures, and the animals in them must have always eaten a good deal of it with impunity. The cultivation of sugar-beet, which has never met with much success here, has now been encouraged by the Government with financial and other support, and it is hoped that it may flourish. An estate in Nottinghamshire has been bought for this purpose. The growth of flax, hemp, and tobacco has been likewise aided by pecuniary grants. Little seems to be known about the flora of New Guinea, a collection of 330 plants made there recently being found to contain no less than 100 which were new to science. As the country is opened up this will no doubt be rectified. An African grass, new to the locality, has suddenly appeared in the Island of Ascension, clothing large bare tracts of volcanic ash with vegetation. An interesting account of the Somme battlefield last summer describes it as clothed with large masses of common flowers-poppies, chamomile, charlock, rose bay willow herb, and others,

covering the traces of the fearful bombardment which had torn its surface and made it in the winter a dreary waste of mud and water. By regularly screening plants of Tropæolum during certain different intervals of the day considerable variations have been induced in colour and scent and even in structure, extra petals and spurs being formed under certain treatment.

GEOLOGY.

The geological age of the earth, that is, as I understand it, the space of time since the first rocks were formed by denudation, has been calculated in various ways which do not all agree. Thus from measuring the rates of denudation now going on, the age of from 100 to 150 millions of years has been deduced. Astronomy gives rather less. Calculations based on heat have been entirely upset by the discovery of the heat-producing properties of radium and radio-active elements, which exist all over the earth's surface. In connection with this discovery the age has, however, again been calculated on the basis of the time required for radium to pass through its transformations and the ratio of the quantity of lead to the quantity of uranium. This gives a much greater time, amounting to 1,500 millions of years; but by more recent investigations of the amount of lead in Ceylon thorite, the age of 140 millions has been found, which is fairly in agreement with some other deductions. There are, however, some reasons for supposing that the decay of uranium may have been more rapid in early times, which would bring down the result of 1,500 millions to a figure more nearly approaching the other conclusions. It has been thought that the apparent greater frequency of earthquakes at night than in the daytime was owing to their being more easily perceived during the quieter hours; but on counting the more intense Italian earthquakes only and omitting the smaller ones it was found that no less than 865 occurred at night to 638 by day, which strongly supports the belief in question. A bad earthquake occurred in New Zealand last August, doing

much damage in the N. Island, and another serious one in San Salvador early in June, 1917. A small movement in the seismograph at Shide in the Isle of Wight is believed to have been caused by the Messines explosion on June 7th at 3.10 a.m., when 19 large mines, containing altogether about 450 tons of explosives, were simultaneously fired, making craters up to a size of 100 yards in diameter and 70 feet deep. Even the Arctic regions are now being worked for coal, which is being brought to Norway from Spitzbergen. it being estimated that this coalfield might produce 200,000 tons per annum. Coal is also found in Bear Island in the same region. To turn to fossils, a most interesting fossil of an Ichthyosaurus, shewing the skin and other soft parts, has been presented to the Natural History Museum from the Lias of Barrow-in-Soar, Leicestershire. The skin of the paddle seems to have been ornamented with rosettes of dark spots. The stomach contained remains of cuttlefish. A nearly complete skeleton of a gigantic fossil bird from the Lower Eocene of Wyoming has lately been added to the American Natural History Museum, New York. It was nearly seven feet high, with a huge head 18in. in length, a large compressed beak, and a massive neck and small wings. A few fragments were discovered 40 years ago and named Diatryma. The skull of a new genus of bats, Zanycteris, has been discovered in a very early Tertiary formation in Colorado and seems to belong to a family still found in tropical America. Other more recent fossil bat remains have been found in caverns at Porto Rico. Specimens of huge fossil Dinosaurs of various species have also been obtained from Wyoming and from the Upper Cretaceous of Alberta and Montana, including a nearly complete skeleton of Monoclonius. These have been described by Professor Osborn.

ASTRONOMY.

In my address last year I alluded to the theory that the force of gravity was slightly affected by the motion of the

bodies concerned; but further experiments have produced negative results, so that the theory is, so far, very doubtful. Rotation has been observed in several more nebulæ during the past year, and the dimensions of the Ring Nebula in Lyra have been computed to be no less than 330 and 250 times the diameter of Neptune's orbit in the longer and shorter axes of the ellipse. This was done by ascertaining the parallax of a star which is associated with the nebula in question. The nearest star to our system is star Centauri, and a faint star in the same constellation has now been found to be at almost exactly the same distance from us. By a spectroscopic method it has been shewn that a definite decrease in the brightness of stars is almost certainly accompanied by an increase in velocity. Many stars have been shewn to possess proper motion of their own. Amongst others one of the 14th magnitude near Arietis has the large proper motion of 1.74in. per annum. The total number of stars down to the 16th magnitude has been estimated at 33,000,000. A small new star associated with a nebula in Cygnus has been discovered, and several others, including one, also associated with a nebula, in Andromeda. In this nebula no less than five novae have been noted of late years. A total eclipse of the sun will take place on June 8th next, the totality lasting from one to two minutes over a belt about 60 miles wide stretching from Washington to Florida. Owing to the war no English expeditions for its observation have been organised; but there will be some American ones. A solar prominence of unusual magnitude was observed on May 26th, 1916, which attained a height of half a million miles and a velocity of 457 kilometres per second, and then faded very rapidly. These prominences have been considered to be connected with sunspots; but some observations, extending from 1904 to the present time, have not shewn this to be the case. On December 3rd last, a meteorite fell in Perthshire, exploding with great noise. Three portions were found, one of 224lb., which penetrated the earth to a depth of 20in., one of 24lb., which struck the lodge at Keithick House, Coupar Angus, and