DECEMBER 20, 1906] 
NEAR U Fee I 
81 
the editorial of the Indian Forester (September), and is 
discussed in a letter from Mr. A. M. Lushington, who 
draws his arguments from a consideration of the 
sources of the Cauvery. Mr. Lushington emphasises the 
necessity of duly conserving the forests at the river sources, 
and suggests that the help of Government should be invoked 
to provide the necessary funds, more particularly where the 
river runs through different States. 
Mucu attention is paid in various parts of India by the 
forest departments to the planting of avenues along the 
roadsides. An article describing the trees suitable for the 
Salem district in Madras, by Mr. F. A. Lodge, is pub- 
lished in the same number of the Indian Forester. Figs, 
the wild mango, the tamarind, and the margosa tree, 
Melia azedirachta, are recommended as a first choice, but 
a more extensive list is given of trees less generally suit- 
able although adapted to special soils. Cultural directions 
are added with regard to setting out nurseries, transplant- 
ing and pruning. 
Tue Bulletin de la Société d’Encouragement (vol. cviii., 
No. 9) contains the oration delivered by Mr. Gruner at the 
funeral of Mr. Huet, the eminent civil engineer, president 
of the society. 
THE report of the judges on the trials of suction gas pro- 
ducers organised by the Royal Agricultural Society has been 
drawn up by Captain Sankey, and summaries of it are 
published in the Engineer and in Engineering of 
December 14. It forms a valuable contribution to the 
literature of the subject, and shows conclusively that the 
suction plant is well adapted for agricultural purposes. 
Although less manual labour is required than with a steam 
engine, more intelligence is required on the part of the 
attendant to ensure the production of gas of good quality. 
In the eleven plants of which complete figures are given, 
the fuel consumption per brake horse-power at full load 
varied between 1-04 lb. and 1-48 Ib. The winners of the 
awards priced their plants at almost the same figure, 
11-651. and 11-771. per brake horse-power. 
ReEcENT developments in aérial navigation form the sub- 
ject of an article by Major Baden-Powell in Knowledge 
for December. Commenting on the prevalent view that 
Santos Dumont’s experiments constitute the first case of 
actual human flight, the author refers to the previous re- 
ported records of the Brothers Wilbur and Orville Wright. 
He also expresses doubt as to how far the recent experi- 
ments in Paris have effectively disposed of the stability 
question. From Major Baden-Powell’s article we further 
learn that experiments with mechanically-propelled balloons 
are still receiving considerable attention. In particular, the 
Zeppelin airship has again been making trips, and a speed 
of thirty miles an hour has been recorded, though it would 
appear that the estimate was made by theodolite measure- 
ments, and further information would therefore have to be 
placed at the disposal of a reader before any conclusions 
could be drawn as to the velocity relative to the wind. 
A new Lebaudy balloon called La Patrie has been built 
for the French Government. Since the appearance of 
Major Baden-Powell’s article it has been reported in the 
Press that a new explosive has been prepared by the United 
States Government for use in aéroplane machines con- 
structed by the Brothers Wright. 
Tue Journal of the Franklin Institute (vol. clxii., No. 5) 
contains a striking illustration of the historical collection 
of more than a thousand incandescent lamps, for which 
the Elliott Cresson gold medal was awarded to Mr. William 
NO. 1938, VOL. 75 | 
J. Hammer, of New York. The collection, made during 
a period covering more than a quarter of a century, 
embodies a history that could not have been recorded in 
words, and could not be reproduced if destroyed. In the 
same issue Prof. Carl Hering describes the Decker battery, 
a new form of primary battery for large outputs. It is the 
usual bichromate cell, the feature of novelty being the 
construction of the cell and its parts. Prof. A. E. Outer- 
bridge reviews recent progress in metallurgy, dealing 
specially with high-speed tool steels, ferro-alloys, steel- 
hardening metals, nickel-vanadium steel alloys, blast- 
aluminium, copper, the great increase 
gold, and the declining production of 
furnace slag cement, 
in the production of 
silver. 
In the Century Magazine for December is an article by 
the Hon. W. H. Taft, Secretary of War, U.S.A., explain- 
ing why the lock system was adopted for the Panama 
Canal. This question had been referred to a commission 
of thirteen of the most experienced ship-canal engineers 
both in the United States and abroad. The majority of 
this commission, eight in number, advised a_ sea-level 
canal, while the minority, consisting principally of the 
American engineers, advised a canal with locks at a 
summit-level of 85 feet above the sea. The final decision 
of the American Government and Congress has been 
accorded to the adoption of the lock system. The reason 
for this may be briefly summarised as follows :—The 
canal without locks would require a deep cutting, a great 
deal of which would be rock, through the summit-level at 
Cuelebra involving the removal of 250 millions of cubie 
yards. The waterway through this cutting would only be 
150 feet wide and 4o feet deep. It was estimated that it 
would take sixteen years to complete the work, and that 
the total cost, including interest on the outlay, would 
amount to about 63 millions of pounds. The lock canal, 
on the other hand, is estimated to cost half the above sum, 
and to occupy only half the time in constructing. The 
waterway will vary from 45 feet to 75 feet in depth, and 
the width from 1000 feet over half the length, 500 feet 
to 800 feet over a third, and for about five miles 200 feet. 
The locks are to be in three flights, with a rise of 85 feet, 
or a total lift of 255 feet. Next to the locks, the most 
important work will be the enormous dam that is to be 
constructed to hold the water from the Chagres River, 
which will form a lake covering an area of 118 square 
miles, and in places eight miles wide, the depth varying 
from 45 feet to 75 feet. The dam will, in fact, be a 
small artificial mountain about 13 miles long, half a mile 
wide at the bottom, and 135 feet high, the depth of the 
impounded water being 85 feet at the dam, the top of 
which is to be 50 feet above water-level. 
THE frequently observed fact that the spontaneous 
ionisation of the air when measured leaden vessels 
appears to be greater than when observed in a chamber 
of any other metal suggests the presence of some radio- 
active impurity in ordinary lead. An attempt to identify 
this constituent is described by Messrs. Elster and Geitel 
in No. 23 of the Physikalische Zeitschrift. The fact that 
a solution of ordinary lead does not give an emanation 
proves that the radio-active element is neither radium, 
actinium, nor radio-thorium. The active constituent re- 
mains in solution when the lead is precipitated as chloride, 
and in this respect resembles radium E and radium F; the 
fact that it shows an a radiation exclusively would suggest 
that it is probably radium F (polonium). Before this point 
can be settled measurements will have to be made of the 
range of its « radiation 
in 
