SCIENTIFIC SUMMARY. 
315 
and in the unproductive weight to be carried. In the merchant-ship the 
load to he carried is nearly independent of the form, and any diminution of 
engine power required to drive the vessel, due to form, is pure gain. In the 
iron-clad, the diminution of engine power, by increasing the length and the 
fineness of the vessel’s lines, involves simultaneously an increase in the sur- 
face to be armoured and of the tonnage of the vessel. Mr. Eeed points out 
that in the only instance in which long and short iron-clads have been tried 
under precisely similar conditions, the six hours’ trial of the Minotaur ” 
(400 feet long) and the Bellerophon ” (300 feet long), when both vessels 
were working at 6,200 indicated horse power, the former made 14-165 
knots, and the latter 14-053, the former having been a somewhat shorter 
time in the water, and having, consequently, a cleaner bottom. So that in 
this case, with the same engine power, the speed of the two ships was 
practically identical. The economy of cost of construction in the type of 
short ships introduced by Mr. Eeed is very considerable. 
liesistance of Armour-Plates. — Dr. Fairbairn has given, in a paper read 
before the Institute of Naval Architects, a full account of the experiments 
of the Iron Plate Committee, from 1861 to 1864, so far as they bear on the 
power of iron plates to resist projectiles, and on the qualities most desirable 
in armour casing. 
Joints of Pipes for Gas and Water Mains. — Mr. Barker has described to 
the Society of Engineers a new joint for pipes, designed to obviate the great 
loss from leakage with the joints in ordinary use. Mr. Barker uses spigot 
and faucet pipes, but he casts on them a coarse pitched screw thread. 
When the spigot is placed in the faucet, one turn serves to screw the pipes 
! up to a bearing, and at the same time a layer of moist cement introduced 
■ into a conical recess is compressed so as to form the joint. 
' Palliser Bolts. — It is proposed to use the Palliser bolts, which have been 
I so successfully applied for armour-plating purposes, for the fish and fang 
I bolts of railway permanent way. The principle of the Palliser bolt has 
already been alluded to in these pages,* and there seems no reason why it 
I should not be as suitable for resisting the impacts to which railway fasten- 
I ings are subjected, as the concussion of proj ectiles. 
I 
j MEDICAL SCIENCES. 
j The Relation of the Osseous Medulla to the Blood. — The British Medical 
Journal, in abstracting a recent paper, by Herr Neumann, in the German 
1 Centralhlatt, calls attention to the fact that Neumann’s startling theory that 
j the marrow developes blood-cells, has received confirmation by the observa- 
j tions of M. Bizzozero. Among other things, this observer says that the 
j condition of the marrow in the bones of frogs in winter, as compared with 
I summer, furnishes an important argument in favour of the theory that 
I marrow is a blood -gland. In winter, the white corpuscles in the blood of 
; the frog are not half so numerous as they are in summer ; and in winter the 
* Vol. iii. p. 538. 
