314 Progress of Invention. 



discovered the means of obtaining the same active principle from 

 very different sources, as theine from tea, caffeine from coffee, etc. 

 This principle undoubtedly produces very important effects on the 

 system, though what precisely these are can only be conjectured. 

 A new source of it has lately been discovered by Dr. John 

 Attfield in the Kola-nut, which is used as an article of food 

 by the natives of Western Central Africa. It is, however, not 

 likely in any way to supersede tea or coffee in these countries. Its 

 taste is not agreeable, and the quantity of theine it contains is very 

 small compared with what is found in tea and coffee. The speci- 

 mens examined were in the dry state, which may have modified the 

 results. Manufacture of Sugar. — By the ordinary mode of pro- 

 ducing sugar from cane juice, a considerable amount of uncrystal- 

 lizable sugar or fructose, in the shape of molasses, is produced : this 

 may be considered as so much waste. The longer the process of 

 boiling and the higher the temperature, the more fructose, the quan- 

 tity being, in ordinary cases, so much as twenty per cent. It was 

 found that cane juice, containing only twenty-six per cent,, after an 

 hours' boiling at 250 degrees in a closed vessel, contained fifty-five 

 per cent. This production of uncrystallizable sugar may be avoided 

 by rapid evaporation in an apparatus which has been termed a 

 " concreter," and which consists of a series of very shallow vessels 

 connected together, the evaporation being effected by hot air. The 

 small quantity of fructose originally in the cane juice is not increased 

 during the process, nor the amount of acid. The sugar thus ob- 

 tained is perfectly dry and solid, and is ready, without further treat- 

 ment, to be sent over to the refiner ; it is said also to be free from 

 that pest, the sugar beetle. The quantity of sugar gained in this 

 way will cause an additional profit of £4 per hogshead. This will 

 ultimately prove, it is hoped, a serious benefit to both producer and 

 consumer. Flying Machines. — The American Government, in- 

 duced by some experiments made by the late General Mitchell, from 

 which it was concluded that a twenty-foot screw fan revolving with 

 a certain velocity, would lift much more than six tons into the air, 

 has ordered the construction of an aeronautic machine on a large 

 scale. It consists of a cigar- shaped copper canoe, strengthened with 

 iron ribs, and having in the centre an engine capable of driving four 

 screw fans having twenty-foot blades. One of these fans is placed 

 above, and another below the canoe, to produce ascent or descent, 

 and one at each end to effect a progressive or retrograde motion ; 

 and the whole, when complete, will weigh, it is expected, only about 



six tons. Wire Gannon.' — A cannon of very peculiar construction 



has recently been constructed, and the American Government has 

 ordered experiments to be made with reference to it. Informing it, 

 the core is of bronze, which is reduced by the boring to the thickness 

 of only a quarter of an inch. Around this, steel wire is wound 

 tightly to the depth of about an inch, the coils being in a diagonal 

 direction, and those of one layer crossing those of the next at right 

 angles ; the whole is then raised to a high temperature and immersed 

 in melted bronze. This mode of construction appears to afford 

 great strength ; 500 rounds were fired without the piece being in 



