May i8, 1888.] 



SCIENTIFIC NEW^S. 



459 



distributed among those who sorely need it. Scientific 

 forestry fully carried out in conjunction with small free- 

 holds would cure all the woes of Ireland, provided that 

 her politicians were simultaneously smothered. 



I met with one remarkable exception to the general 

 absence of commercial enterprise in timber cultivation in 

 Ireland : this where I least expected to find such enter- 

 prise — viz., in the Carthusian Monastery of Mount Melle- 

 ray, where the monks and lay brothers have for many 

 years past been planting about 30,000 trees annually, and 



Sectional View of DiSArrEARiNc Gun Turret. 



thus have created a rich forest on a slope of the Knock- 

 mealdown Mountains. (The monks hold a lease for 999 

 years at is. 5d. per acre.) This thriving forest contrasts 

 with the dreary waste on either side ofthe same slope, and 

 strikingly demonsti-ates the possibilities of such cultivation. 

 A neighbouring landlord near Cappoquin has followed 

 their example, and thus another forest has been created 

 with a further and very interesting result. Timber being 

 on the spot, with a supply of water power, saw-mills have 

 been evolved, and these again have induce^ the evolution 

 of factories for the manufacture of doors, wheelbarrows, 

 window sashes, wagons, etc., etc. This is merely a 



natural repetition of what has occurred in Norway, where 

 wooden houses with all their furniture are manufactured 

 for exportation, and every other imaginable and some un- 

 imagined wooden articles and wooden products — such as 

 paper — have followed the supply of crude material. 



A DISAPPEARING GUN-TURRET. 



'T'HE importance of armour-plated turrets for cannon 

 in the defence of fortified places has latterly in- 

 creased, since neither masonry nor earthwork can 

 resist the impact of hollow projectiles filled with so- 

 called " high " explosives. The first step, therefore, 

 was to mount cannon in revolving iron towers, so 

 contrived that, immediately after firing, the embra- 

 sures could be turned away from the enemy for 

 reloading. A further step was the adoption of the 

 eclipse principle, where the revolving cylinder not 

 merely turns on its axis, but can be raised or 

 lowered at the pleasure of the operator. Thus its 

 appearance above ground is only momentary, and 

 does not exceed on each occasion the length of 

 time required for firing. 



The cylinder then at once descends entirely 

 below the ground, where it is solidly encased and 

 protected from the enemy's fire. 



Several modifications of turrets on this principle 

 have already been suggested, and we give here 

 the figure and the description — borrowed from La 

 Nature — of the construction recently proposed by 

 Colonel Souriau, of the French army. 



To obviate the difficulty of using complicated 

 machinery requiring the attendance of experts for 

 the manipulation of such an excessive weight, the 

 inventor founds his construction upon the principle 

 of the indifferent equilibrium of bodies plunged in 

 a liquid. 



The figure represents a hydrostatic turret T T, 

 resting by the intervention of a cylinder C upon 

 a plunger P. This consists of a hollow sheet-iron 

 cylinder immersed in a reservoir of water. The 

 cyhnder C, which projects out ofthe water, sup- 

 ports the part T T. The plunger is of such dimen- 

 sions as to be in equilibrium with the entire part 

 out of the water. Hence it follows that an incon- 

 siderable effort suffices to produce the vertical dis- 

 placement of the whole, which effort may be that 

 of a few human arms acting upon a simple 

 mechanism. A model examined by the engineers 

 at Creusot requires^only four men to bring it into 

 position in fifteen seconds, and to make it again 

 disappear in the same length of time, the ascent 

 and descent thus taking only half a minute. 



All the portion E E capable of emerging is armed 

 v.'ith Creusot plates. It is the same with the dome, 

 which is divided into segments. The cannon-chamber is 

 enclosed in an outer cuirass A A, which serves as a 

 lining to the masonry M M. The turret T, the cylinder C, 

 and the plunger P form an inflexible system well guided 

 by the pivot H. The apparatus is thus well able to 

 resist the shock of the enemy's projectiles. 



The movements of rotation and " eclipse " are con- 

 trolled by one person from the platform /, which is fixed. 

 The movement of rotation is obtained by gearing / 1, 

 working at two speeds. It is fixed to the lower part of 

 the outer cuirass, and is connected with the vertical 

 pinion /'. This pinion works a cogged crown d attached 



