Z 
August 13, 1885 | 
Let each apportion a part of the calculation, and then print it in 
an agreed form. The sterotype plates would be interchanged, 
and what a private firm does the Government can effect. In 
this way the English-speaking marine, including many Dutch 
and German captains, will be at once supplied, and part of the 
proposed economy and benefit be obtained without waiting for 
negotiations with France and Germany. HYDE CLARKE 
Electrical Phenomenon in Mid-Lothian 
I HAVE observed in a daily contemporary a communication 
quoted from your journal with reference to this occurrence on the 
23rd ult. 
For the information of those of your readers who are interested 
in such matters perhaps you will kindly allow me to observe 
that I also witnessed a similar, or the same, phenomenon that 
evening. 
When driving home from a professional visit in the country, 
and a mile south of this town, about ten o’clock I was suddenly 
startled by a peculiar sensation or slight shock, and immediately 
perceived, ten yards in front, on the road, a bright opalescent 
luminosity which travelled deliberately away in a northerly 
direction. This cloud or wave of light covered the whole 
breadth of the road, and was distinctly visible for some seconds. 
It seemed to rest entirely on the ground, and in character 
reminded one somewhat of the illumination resulting from the 
electric light. I should imagine it was travelling at the rate of 
twenty miles an hour, as it was going much in the same direction 
I was, but of course much faster. The part of the road where it 
showed itself is lined by high trees on both sides in full foliage. 
T heard no thunder and saw no lightning or meteor to account 
for the strange and weird-looking light. 
The interesting question then arises, What was the nature of 
this phenomenon ? 
It will be remembered that the thermometer was for several 
days at that time above 80° F. in the shade. Might it not 
be possible, therefore, for a certain volume of air to become 
electrified, and then, perfectly insulated by the dry surrounding 
atmosphere, show its existence in this manner as a luminous 
cloud rushing along the ground? 
I may mention in conclusion that my groom, who was driving 
me at the time, also witnessed the occurrence. 
Dalkeith, N.B., August 10, 1885 RosBertT Lucas 
On a Radiant Energy Recorder 
A FEw weeks ago I wrote a short article for NATURE under 
the above title, describing an instrument for the measurement of 
radiation in heat units which was based upon the principle of 
the integration of temperature by the distillation of water in 
vacuo. Since then Mr. Edward Vivian, M.A., has kindly 
written me a very interesting letter, in which he says that he bad 
seyeral forms of an instrument based upon essentially the same 
principles, made for him by Messrs. Negretti and Zambra many 
years ago, and that some of them are still in use in his garden at 
Torquay. Mr. Vivian’s instruments were shown at the British 
Association (B. A. Report, 1856, p. 48) and at the Royal Insti- 
tution of Great Britain (Yowrnal R. 7., 1857, p. 438), but no 
description of them appears to have been printed, which probably 
accounts for their not being more generally known. 
University College, Liverpool J. W. CLARK 
Our Ancestors 
THE number of ‘‘Our Ancestors” since ‘‘the time of the 
Norman Conquest,” mentioned in your last issue by ( 2 y and 
; 2 
the consequences to be deduced therefrom, have been very 
interestingly discussed already by Mr. Grove in his presidential 
address to the British Association at Nottingham, 1866. 
Freiburg, Badenia, August 8 
THE INSTITUTION OF MECHANICAL 
ENGINEERS 
ee Institution of Mechanical Engineers held their 
summer meeting at Lincoln last week, under the 
presidency of Mr. Jeremiah Head, who, in his inaugural 
address, treated of the relative advantages of iron and 
steel for the various purposes for which these metals are 
NATURE 
343 
employed. The reasons why steel vaz/s are now used 
almost to the exclusion of iron are that they can be pro- 
duced more cheaply, can be manufactured of equally good 
quality by either the Bessemer or Siemens process with 
either acid or basic-lined vessels and of almost any iron 
ore, and they can better withstand abrasion, disintegra- 
tion, or crushing under heavy rolling loads ; for the same 
reasons steel tires are now almost universally employed. 
For ship-building steel is superior to iron, as, owing to its 
greater ductility, ships built of the former metal are able 
to outlive collisions and minor accidents that would be 
fatal to iron ships. As is well known, owing to the 
superior tensile strength of steel, Lloyd’s Committee 
agreed in 1877 to allow a reduction of 20 per cent. in 
weight of scantlings over iron, and in the thickness of 
plates ; Mr. Head argues that, considering a ship’s plate is 
a broad girder, its strength diminishes as the square of 
the thickness, and that, therefore, although a steel ship 
would be superior to an iron one of equal: weight, 
an iron ship is likely to retain its form better than 
a steel one built 20 per cent. lighter. As regards dridges 
and roofs, the employment of iron or steel depends 
mainly upon the size of the structure ; for light edifices, 
owing to its greater cheapness, iron has hitherto been 
used, whilst for large spans, where the weight of the 
structure itself is an important function, steel has been 
employed in the erection of bridges of spans which could 
not have been attempted if the engineer had been 
dependent on iron alone. For Jéoz/ers, except in the 
matter of corrosion, in which authorities seem to differ 
as to the resisting power of iron and steel, but appear to 
be rather favourable to the former, steel is much more 
advantageous than iron, both on account of its being as 
cheap, and on account of a steam boiler of the same weight 
being able to withstand much higher pressures if made 
of steel than if made of iron ; hence boilers, and marine 
boilers particularly, are now scarcely ever built of iron. 
The President recommended the application of metal in 
the construction of the frames of rolling stock and for 
railway-sleepers. As regards the continued use of wooden 
sleepers, there can be no question that “it is a form of 
waste that should be reprehended in the public interest, 
just as should the use of coal for ballasting or other 
obviously wasteful purpose. The same timber which 
would become useless for sleepers in, say, nine years, 
would last at least a century in the roof or flooring of a 
house.” Another argument advanced, and a most im- 
portant one, is that the substitution of iron and steel for 
timber railway-sleepers would not only give an enormous 
impetus to these industries while the substitution was 
being effected, but would permanently maintain a popu- 
lation of 100,000, or 3 per cent. of the whole population 
of the country, for renewals. . 
Leaving special branches of industry, to refer to special 
forms in which iron and steel are supplied, the President 
drew attention to dav-zron still maintaining its position, 
because wherever implements are ade they come sooner 
or later to the village blacksmith to be vefazred, and these 
find steel harder to work, more difficult to weld, and re- 
quiring more care to smith; and therefore the original 
manufacturer has to adopt a material and construction 
within the compass of the ideas and resources of the rural 
repairer. 
As regards castings, an urgent need has long existed 
for a material which could be cast in a mould, and which 
should yet have the toughness and tenacity of wrought 
iron ; and steel, exactly supplying this want, has come 
very generally into use, more particularly as the cost of 
steel castings has been greatly cheapened latterly by the 
employment of the Bessemer and Open Hearth piocesses ; 
still, steel castings are much dearer than iron ones, 
because the molten metal is dearer, and the higher 
melting point of steel compared with iron necessitates more 
costly moulds. But in a majority of cases in which cast 
