Another form of dress largely in use enables the diver to descend in shallow water without relying on the usual air-pipe and pump. In such dresses the diver carries certain chemicals which not only purify the air he is breathing, but also furnish him with fresh oxygen. One chemical absorbs the poisonous carbonic acid gas given off by the breath, and the other chemical gives off fresh oxygen as the moisture of the breath touches it. The smoke helmet which enables men to enter a mine after a disaster, or a building full of foul fumes, is equipped with the same chemicals and made on the same principle as the diving dress. Instead of completely covering the man, however, this dress is made like a jacket reaching to the waist, where it is securely buckled. In this dress it was impossible to penetrate the Redding pit, near Falkirk, from which five miners were marvellously rescued after being entombed for nine days, so several naval divers in regulation dress risked their lives in an effort to penetrate the workings to see if any other men still survived and to carry stimulants to them. Divers, at best, have the appearance of creatures from another world, and the effect of a diver, with his lamp, emerging from the inky water and coming suddenly on men who had been immured for a fortnight without food and were at their last gasp had to be carefully considered. Some of the survivors might have attacked him in their delirium and deprived their comrades of all chance of succour. To avoid so untoward an incident, the leading diver carried with him a message for those men he hoped to find: “This is a diver come to save you. Don’t touch him, as he cannot speak to you. We are driving a place for you. Don’t sit down near the water, but keep clear of the damp. If any of your mates are far through, turn their heads downhill and that will help them until you are feeling stronger. The diver cannot come up the hill out of the water to help you, because his tools are too heavy. He will come back regularly and feed you. You must not drink more than half a cupful of beef tea each. Wait and take a rest before you drink another half-cupful. On this paper write who you are. You will be got out soon.” Alas, for human endeavour, that message never reached the poor fellows for whom it was intended! The great falls of roof choked the roads and proved an insurmountable barrier. Raging, but exhausted, the divers had to bow their heads in defeat. So commonplace is the diving dress that it no longer excites curiosity. Yet it remains one of the wonders of modern civilization. Merely by utilizing the sap of a tree, which we know as rubber, and fresh air, men are now able to work and live at the bottom of the sea. CHAPTER V