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perfectly solid. In almost every case they were completely perforated by 
the 7 -inch gun, with Palliser chilled shot, and charges of 15 to 20 lbs. of 
powder. One iron and one steel-faced plate resisted complete perforation, 
with the smaller charge, and the most that can be concluded at present is, 
that the laminated steel and iron plates exhibit equal resisting powers to the 
best rolled iron plates hitherto produced. It is remarkable that the chilled 
hot which penetrated but did not get through the plates remained perfect 
and unbroken. 
Flow of Solids. — M. Tresca has explained to the Institute of Mechanical 
Engineers, now holding a meeting at Paris, his views on the flow of solids, 
to which we have before alluded. The experiments on which M. Tresca’s 
theory is founded are of this nature. If a hollow cylinder closed at the 
bottom end, have a cylindrical block of lead fitted to it, and the hollow 
cylinder have a round hole in the centre of the bottom, a powerful pressure 
on the top of the block will produce a cylindrical jet of metal, having a 
section equal in area to the hole in the cylindrical vessel. If the solid block 
be replaced by a series of parallel laminae of the same substance, and a 
section of the block be made after the pressure has been applied, it will be 
found that the laminae, though compressed, remain parallel and flat over all 
the surface excepting that affected by the formation of the jet, and the jet 
itself will be found to consist of a series of cylindrical envelopes or tubes, 
one for each lamina of the original block. The same results have been 
obtained by M. Tresca with tin, silver, copper, aluminum, iron, steel, and 
other substances. If a series of holes be made in the bottom of the 
containing vessel, then a series of jets are formed, but each jet more or less 
affects the formation of the others. M. Tresca has similarly studied the 
flow through lateral orifices and the unequal distribution of pressure in the 
mass, due to the flow, and he has applied these results to explain the opera- 
tions of forging and rolling. By oxidising specimens of rolled and forged 
iron, he found that all the elements of the original piece are drawn out in 
parallel lines, from the surface to the centre of the bar ; precisely as in 
the case of the jets produced by pressure ; so that, the changes of form 
produced by forging may be considered as the results of successive flowings, 
effected by each of the individual forces exerted on the work forged. These 
changes of form take place from particle to particle according to a geome- 
trical order which admits of mathematical calculation. And the theory 
may thus supply definite rules for metallurgical operations. An abstract of 
the paper, which is extremely interesting, will be found in the Engineer of 
Jure 7. 
MEDICAL SCIENCE. 
Development of Fungi in the Kidneys. — In the last number of Beale's 
Archives , Dr. M. Tonge gives the details of a curious case of Phthisis, ac- 
companied by the development of fungous growths in the substance of the 
kidney. The pelvis of the left kidney was filled with a yellowish-white 
