I 4 2 
Progress in Science . 
[January, 
Mr. Hugh Leonard, M.I.C.E., Chief Engineer under the Government of 
India, has published in “ Engineering” a memorandum drawn up by him on 
“ The Weight on Foundations of Buildings.” Mr. Leonard was led to enquire 
into this subject when commencing several new buildings in Calcutta, several 
buildings of recent construction being cracked, and some of them badly. The 
conclusions drawn, after a long series of experiments, were as follows : — “ If 
it be desired to provide against sinking of the whole stru&ure, the weight per 
foot on the earth, whatever may be the depth at which the foundation is laid, 
should not be more than one ton per square foot; and that, if unequal sinking 
cracks are to be provided against, the weight on all parts of the foundations 
should be equal per square foot, unless that the most heavily-loaded portion 
carries less than one ton per square foot. With this weight, and, of course, 
with lighter weights, no perceptible compression takes place, and hence no 
unequal settlement would occur from unequal loading.” From experiments 
relative to the best depth for the foundation, it was ascertained that shallow 
foundations have the disadvantage of being affedted by climatic influence, as 
heavy rain caused the masonry laid at a depth of 2 feet 6 inches below the 
surface to sink considerably. “ Again it appears that foundations laid at a 
depth of 11 feet below the surface sink more than those laid at depths of 
4 feet and 8 feet.” The conclusions drawn from these experiments were that 
“ the foundations of important buildings should be laid so deep that they 
cannot be affedted by climate,” and that they “ should not be laid at a less 
depth than 4 feet, nor a greater depth than 6 feet.” The last series of experi- 
ments undertaken were to ascertain the strength of spread foundations, and the 
conclusions drawn from them were that “ for a pressure of one ton to the foot, 
on Bengal soil, the thickness at the toe of the slope should not be less than 
1 foot 6 inches, and the stepping at an angle of not more than 45°. 
A new market-place has recently been opened in Madrid, the materials of 
which were all sent out from this country. In design these markets are some- 
what similar to the Halles Centrales in Paris, but are bolder, more ornamental 
in charadter, and very lofty. Strudlurally, the markets are composed of separate 
pavilions, the Mostenses Market having three, each 127 feet long and 90 feet 
wide, the pavilions being connected by passages, making altogether a 
rectangular area of 38,500 square feet. The Cebada Market covers an irre- 
gularly shaped area of 60,000 square feet, and is composed of four principal 
pavilions, each 119 feet long and 79 feet wide, three irregular pavilions and one 
lofty central dome, the pavilions being connedled by covered ways, as at 
Mostenses. In these two structures there is nearly 4000 tons of cast- and 
wrought-iron. Below each market the space is utilised for cellars, the ground- 
floor being supported by cast-iron stanchions. The roofs are covered with 
galvanised corrugated iron, and there is ample ventilation by open louvres in 
the roofs and sides of each pavilion. 
Electricity. — The following process has been recently invented in France 
by M. Hausen, for depositing metallic coatings upon glass or porcelain: — Sul- 
phur is dissolved in oil and lavender and evaporated to a syrup; chloride of 
gold or of platinum is also dissolved in ether. The two solutions are mixed 
and slightly heated. They are finally evaporated to the consistence of ordinary 
oil-paint, and applied with a pencil to those parts of the glass or porcelain upon 
which it is desired to deposit the metal by the battery. 
An apparatus consisting of two movable parts has been constructed by 
MM. Terquem and Trunnin for perforating glass with the electric spark. In 
the upper part of the apparatus a vertical brass rod, with ball above, point 
below, is enclosed in two concentric glass tubes, the small intervals being 
filled with colophonium. The brass point reaches through to the lower side of 
a horizontal glass plate attached to the tubes. In the lower part of the 
apparatus a right-angled brass rod is fixed, also in colophonium within a glass 
tube, its vertical part passing up the middle, and terminating in a point on the 
upper side of a horizontal glass plate resting on the tube. The tube is sup- 
ported on porcelain and wood. The plate to be perforated is first coated with 
