[Sidenote: 43. Four-line Track with London and North Western Express.] [Sidenote: 44. In a Travelling Post Office.] Here is a large corn mill, and here the interior of such a mill. The grain is lifted from the importing ship and carried on these straps, running on rollers, to the place where it is to be stored. And here is a scene of interest to all Britons who go to the remoter frontiers of the Empire. It represents the packing of biscuits in tin boxes for export. The food having been imported is carried into all the land by railways. The British railways are, of course, relatively short, but run through dense populations, and are probably the most efficient in the world. Here is a recent express engine capable of hauling a passenger train without stopping for 300 miles. Next we see such an express running on a four-line track and picking up water for its boiler from troughs laid between the rails. Time is very valuable in Britain. Here, as an instance, is the interior of a travelling post office, which runs on express trains. The letters are sorted on the road, and the mail bags thrown out and caught up at fixed points while the train runs. [Sidenote: 45. The Forth Bridge.] Perhaps the grandest feat of engineering in connection with the British railways is the Forth Bridge. See how small the houses appear when compared with it. [Sidenote: 46. Electric Power Station, Chelsea.] [Sidenote: 47. Electric Train on Metropolitan District Railway.] But another revolution in all the conditions of British life is now preparing. Electricity is being used to distribute power from great fixed engines, and locomotive steam engines have already been displaced on the shorter lines. Here is part of the interior of the largest power station in the world, where is generated the electricity for four railways which traverse London. This is the boiler house, with automatic stokers. And last we have an electric train. You note the absence of a locomotive. Thus we see how the 43 million people of Britain co-operate in a single vast complex machine. But we must remember that it is not only the present generation which has made Britain such as we see it, but many millions in the past, the results of whose work we of to-day have inherited. LECTURE VII. THE DEFENCES OF THE EMPIRE. Though we are so many miles away, I think you will agree that in the past six Lectures we have seen something of the two islands which are the centre of the British Empire. These islands are interesting to us because the great Empire of which we are a part has grown from them. Let us devote this last Lecture to the Empire as a whole. Let us learn how it is held together, and how it is defended, so that there may be peace and justice in all its parts. [Sidenote: 1. Map of Empire with Naval Bases.]