6 5 6 



SCIENTIFIC NEWS. 



[Dec. 28, 1888. 



generative apparatus appear to be wanting. Clearly, 

 theory the first is not correct. 



Theory the second, although nearer to the truth, is 

 also open to fatal objection, for in no animal do we find 

 organs or members which are not present, although very 

 likely in a greatly modified form, in thousands of other 

 species. Thus to hold that the explosive apparatus of 

 these remarkable beetles is absolutely unique is probably 

 true only insomuch as it does not appear to be present 

 in other insects in precisely the same form. And we know 

 that great numbers of insects do possess an apparatus 

 which at least is somewhat similar in character. Thus 

 most of the Geodephaga emit when handled a volatile 

 and evil-scented fluid, not only from the mouth, but also 

 from two small glands situated near the tail — just the 

 region, it will be noted, in which lie the secretory organs 

 of the Brachini. And some of these can eject the liquid 

 in question to a distance of several inches. The well- 

 known Musk Beetle (Cerambyx moschatus) has under 

 exceptional conditions been known to do the same. Ants, 

 again, expel formic acid when annoyed, and cause con- 

 siderable pain and irritation if the face be held near to a 

 disturbed nest ; and some of the Hemifitera possess a 

 somewhat similar power. Thus it would seem that the 

 explosive nature of the Bombardier's discharge is merely 

 due to the fact that the liquid which it secretes is of a 

 more volatile character than usual, passing at once into 

 vapour when expelled instead of evaporating by degrees. 

 And so we have the key to the mystery. 



FLINTS* 



PROFESSOR JUDD said that on that evening he pro- 

 posed to speak to them concerning the uses to which 

 flints could be put. It must be confessed at the outset 

 that the uses to which flint could be put at the present 

 day were 'greatly restricted as compared with those 

 to which it had been put in the past. At the present 

 day they sometimes employed flint as a road-metal, and 

 for this purpose, though it answered fairly well, yet it 

 was generally inferior to many of the hard igneous rocks 

 like the well-known dhu-stone employed in the London 

 streets. Flints were sometimes ground and reduced to 

 powder, the powder being employed in the manufacture 

 of glass and porcelain. There were a few gentlemen of 

 dandified manners and conservative instincts — he did 

 not mean politically — who preferred to use a flint and 

 steel mounted in silver rather than the ordinary wax 

 vestas and fusees employed in lighting pipes and cigars; 

 and, lastly, muskets with flint locks are still prepared 

 for somewhat unsophisticated savages, though the most 

 unsophisticated savages of all were supplied, it is said, 

 with muskets without touch-holes. Among savage nations 

 flint was still largely employed for many purposes. But in 

 nations where the arts had become known, the use of metals 

 had to a very large extent displaced the use of flint and 

 other stones. Among savage nations, however, flint and 

 similar materials were constantly employed either for 

 obtaining fire or for making tools and weapons. 



Now, let them inquire for one moment what were the 

 properties of flint which enabled it to be used in that 

 particular way. These properties, which he had already 

 referred to in a former lecture, were, first, hardness, 

 which enabled it, when struck with pyrites or steel, or 

 any hard substance, or even with another piece of flint, 



* Sixth Lecture to Working Men at the Royal School of Mines. 



to emit sparks, and also enabled sharp flints to be used 

 for cutting purposes ; but with this hardness was com- 

 bined a certain amount of toughness, so that it preserved 

 a sharp edge much longer than a piece of glass or similar 

 material, which was sometimes employed for the same pur- 

 pose. Most remarkable of all was the conchoidal fracture 

 to which he had called attention, which enabled fragments 

 to be struck off, having the remarkable form of flakes. 

 They would recollect what he said about flakes, with 

 their bulb of percussion, and which enabled them to be 

 trimmed so as to form weapons and tools of very de- 

 finite form. Then there were two other properties which 

 had some influence upon flint. First, the porosity; the 

 porosity of flint allowed water to be absorbed and to 

 be driven off by the ordinary drying process ; so that 

 flints were sometimes moist throughout and sometimes 

 dry, and their other properties changed with the quantity 

 of water they contained. Lastly, they had this important 

 property, that flints, although, geologically speaking, they 

 withered away, yet, spoken of historically, they were 

 among the most unchangeable of things ; so that, whereas 

 weapons of iron and bronze, and even gold and silver, 

 had perished, articles made of flint were almost im- 

 perishable, though even many of these worked flints 

 could be seen on the exposed surface to be undergoing 

 the first stages of decay, such as the flint exhibited, 

 which had been covered in one position, where the 

 original black surface was preserved, and on the other 

 side there was a thin white coating, due to disintegra- 

 tion. Now, perhaps he ought to mention that different 

 examples of flint exhibit very great variations in the 

 degree to which they possess these several properties. 

 Some flints differed greatly from others in their uni- 

 formity and fineness of grain. There were some flints 

 which were wonderfully uniform in texture throughout 

 their mass. These lent themselves to being fashioned 

 in the most beautiful forms, whereas there were others 

 which showed great irregularities in grain. In one 

 part the structure was fine and in another part it 

 was coarse, and thus they did not lend themselves 

 to be fashioned with the wonderful beauty that they 

 would see that certain flints were susceptible of acquir- 

 ing. Now let them inquire what were the methods of 

 making and using objects of flint and other similar stones ; 

 and the methods employed both in making and using 

 flint weapons could only be judged of by studying 

 similar weapons used by savage tribes at the present 

 day. In many countries the use of stone was still com- 

 mon. In Australia, among savages there, and in the 

 South Sea Islands, the use of metals is unknown — the 

 art of extracting metals from the ores is quite unknown, 

 and if they used metals at all, it was only metal which 

 had been derived from the white man. As a rule their 

 weapons and tools were all fashioned from stone. They 

 had, however, sometimes an opportunity of understand- 

 ing how the ancient weapons and tools were used by the 

 early people who made them, for occasionally, as in peat 

 mosses and similar situations, they might find the 

 handles or the attachments of the tools actually preserved, 

 and they might study the manner in which they were used. 

 Let them examine first the methods which must have 

 been employed by the ancient workmen in fashioning the 

 tools and weapons which they employed. With regard 

 to those weapons and tools, he might mention that they 

 sometimes used ordinary flint-pebbles, masses of flint 

 which had been washed out of the chalk and rolled into 

 pebbles. These were generally of a brownish, reddish, 



