Some of our engineers and naval men are greatly interested in a subject which has, from time to time, during many years, met with a passing notice--namely, the gradual growth of the banks and shoals in the North Sea from the solid matters carried into it by the rivers of England and Holland. Although slow, the increase is said to be such as to lead to the inference, that this sea will be filled up at some future day. A large chart has just been published, with contour lines of the various banks, to illustrate a treatise on the subject. If these be correct, we have at once valuable data by which to test the question of increase of magnitude. The matter will shortly be discussed by one of our scientific societies. Meantime, the reclamation of a new county from the sea is going on on the Lincolnshire coast; and there appears to be a prospect of a similar work being undertaken on the western shore--at Liverpool. Mr G. Rennie has prepared a plan for a breakwater five miles long, to be constructed at the mouth of the Mersey, stretching out from Black Rock Point. If carried into execution, it will reclaim a vast extent of sandbanks lying within it, and greatly improve the navigable channel of the river. A proposal has been made to apply sewage manure to the reclaimed land, in such ways as will constitute a satisfactory trial of this means of fertilisation; and also to reserve suitable portions as sites for building societies. Such a project as this would be worthy of the enterprise of Liverpool; but it would be well for the promoters to bear in mind a fact which has lately been urged, that by encroaching on the space of an estuary, you prevent the inflow of the tide, and consequently diminish or weaken the outflow, whereby the whole harbour becomes shallower, and the bar at the mouth augments in bulk.
Although there is nothing extraordinary to talk about in the way of scientific discovery at present, workers in science are not idle, and are steadily pursuing their investigations. Faraday has added another chapter to his 'Experimental Researches in Electricity;' Mr Grove has contributed somewhat to our knowledge of the 'Polarity of Gases;' a paper by Mr Wharton Jones, entitled 'Discovery that the Veins of the Bat's Wing (which are furnished with Valves) are endowed with Rythmical Contractility, and that the Onward Flow of Blood is accelerated by each Contraction,' is considered to be decisive of a question of some importance in physiology--namely, that the circulation of the blood in the wings is independent of the motion of the heart. Mr Huxley's paper in the Philosophical Transactions is also a remarkable one--one of those which really constitute progress. Although it is not easy to give a popular exposition of it, I may tell you that it discusses the subject of 'alternate generation;' a favourite one, as you will remember, with several naturalists, according to whom, certain of the _Medusæ_ are of one sex at one period of their lives, and of the other sex at another. But Mr Huxley shews, by observation and experiment on _Salpa_ and _Pyrosoma_, that each has independent powers of reproduction, and his facts are conclusive against the theory of 'alternation of generations.' The two generations, as now appears, are not of distinct individuals, but are both required to make a complete individual. This paper will be sure to provoke criticism, and perhaps excite further research. Mr Hopkins has been enlightening the Geological Society 'On the Causes of the Changes of Climate at Different Geological Periods;' and assigns as one of the causes, the flowing of the gulf-stream in a different direction formerly to that which it follows at present, whereby the northern ice was brought down in great masses to form our glacial period.