— 
Nov. 24, 1870] 
NATURE 
69 

This was preceded bya hailstorm and rain, with occasional 
breaks in the clouds, through which we observed four meteors 
between 5 and 6.30 A.M. 
On the evening of the 14th the sky was only half covered with 
clouds from 5 to 8 p.M., and eight meteors were observed be- 
tween 5.48 and 6.40; one at 6.2 was of a brilliant red colour, 
with a pale greenish white train. 
From 7.40 to 8.35 five other meteors were seen. The sky 
cleared for a short time towards 8 P.M., but at 9 a mist came on 
which obscured the heavens during the remainder of the night, 
clearing off, however, occasionally for a short time. I will not 
trouble you with the path of each separate meteor, though each 
was carefully noted. From the above observations I should 
be inclined to think that we had passed through the maximum 
during the afternoon of the 14th. Had there been any brilliant 
display during the night of the 14th, I think it would hardly 
have escaped me in spite of the mist. 
Stonyhurst Observatory S. J. Perry 


SPAIN AND THE ECLIPSE EXPEDITION 
as following is a translation of a letter which appears 
in the Astronomische Nachrichten for Nov. 15, on 
the facilities offered by the Spanish Government to such 
foreign astronomers as purpose visiting Spain on the 
occasion of the approaching eclipse :— 
“ MADRID, JVov. 5. 
“T have the honour to inform you that the Spanish 
Government, at the request of the Observatory at Madrid, 
and in accordance with the resolution taken at the time of 
the eclipse of the sun in 1860, has just agreed that similar 
measures shall be adopted for facilitating to foreign 
astronomers the observation of the approaching solar 
eclipse on the 22nd of December of the present year. 
The Government has in consequence resolved,— 
“That at the Spanish Custom Houses no duty or 
deposit shall be demanded on the astronomical or physical 
instruments that astronomers bring into Spain for the 
observation and study of the eclipse.’ 
“But as this privilege, which has been granted with 
readiness to astronomers, might be taken advantage of 
by persons noways connected with Science, the Govern- 
ment has deemed it necessary to adopt certain measures 
of precaution, the principal one of which is, to be made 
cognisant of the names of the persons who are making 
preparations to come to Spain to observe the eclipse. In 
consequence thereof, the Minister of Finance has directed 
‘that such astronomers as purpose availing themselves 
of the resolution above spoken of should have the good- 
ness to make known in writing to the Observatory at 
Madrid their names, the number and the class of instru- 
ments which they bring, and the point of the coast or 
frontier where they purpose entering Spain.’ These 
particulars will be communicated by the Observatory to 
the Government, which will send orders to the Custom- 
houses to pass without difficulty all the instruments entered 
on the lists the astronomers furnish. Foreign astronomers 
may, moreover, reckon on the sedulous protection of the 
provincial governors and of the local authorities, from 
whom they will receive all the co-operation necessary to 
enable them to devote themselves with entire liberty to 
their scientific labours. 
“Inthe Almanac of the Observatory ef Madrid for 1870 
(which you have not received owing to the want of com- 
munication with Germany for several months) there 
is contained a somewhat detailed account of the 
approaching eclipse, accompanied by two maps. As you 
will observe, in the zone of the total eclipse there have 
been inserted all the principal towns, in order to assist 
astronomers in the selection of their stations for observing. 
This central line is not of great dimensions in Spain 
(about sixty nautical miles) yet, nevertheless, there are 
numerous important towns in proximity to the central 
line, as, for instance, San Lucar, Jerez, Puerto de Santa 
Maria, Puerto Real, San Fernando, Cadiz, Medina Sidonia, 
Estepona, and at those places observers {will meet with 

all the resources requisite for carrying out their labours 
with facility. The sole disadvantage of so short a line is 
that if the weather should prove unpropitious at one 
station, it will probably beso at the others as well 
“Tf you think any further details necessary, or in the 
case of any astronomer wishing to consult the map of the 
eclipse, nothing more will be necessary than to apply to 
the Director of the Observatory at Madrid, who tenders 
his services to such foreign astronomers as require them, 
and to whom it will afford great pleasure to aid his col- 
leagues in bringing their scientific mission to Spain toa 
successful result. ANTONIO AGUILAR” 

THE CONSTRUCTION OF HEAVY 
ARTILLERY 
I N few other manufactures has it been found necessary 
to search so deeply into the materials nature pro- 
vides in order to find out the best and strongest, and 
then to apply it skilfully, so as fully to develop its 
strength, as in the manufacture of guns. The construc- 
tion of the amazingly-powerful ordnance which modern 
naval warfare employs is pre-eminently a question of 
strength of material; indeed, it may be termed ‘Zhe 
question of strength of material. In nothing else does 
man employ forces even nearly so powerful and violent. 
The force of steam, even when doing its mightiest work, 
is but faint and small compared with that of the exploding 
| charge of gunpowder that sends from the gun a 3o0olb. or 
60o0lb. shot with a velocity which carries it through thick 
armour plates of wrought iron. A Goolb. shot will pierce 
twelve inches of iron at 200 yards distance. This gigantic 
force is imparted to the shot in the brief fraction of a 
second that it is moving down the barrel of the gun. 
Remembering that “the gain in power is loss in time,” 
and consequently that when the time is diminished the 
power is proportionately increased, we may form some 
conception how enormously great is that force which is 
exerted within the breech of a heavy gun, and which is 
resisted by it every time it is fired. It isa force which, if 
turned into foot pounds, would represent the steam power 
not of a ship but of a navy. Yet all its work is to be 
done in the space of a few inches, and it must be sur- 
rounded with iron strong enough to resist it. Here we 
have the skill of man grappling with enormous difficulties, 
searching out the strongest and most suitable material that 
nature supplies, and exerting all his art to apply it to the 
utmost advantage. The construction of these exceedingly 
powerful guns has been entirely developed within the last 
few years. The gun now manufactured in Woolwich 
Arsenal is more unlike the gun of 1850 than the gun of 
1850 is unlike that of Queen Elizabeth’s reign. The 
progress of twenty years surpasses that of three centu- 
ries. And the change has not been so much in enlarge- 
ment of size as in difference of construction. Queen 
Elizabeth’s pocket-pistol is not more unlike a 600-pounder 
in external appearance than in internal structure. The 
gun which is carried in the turret of one of our ironclads, 
and which, at a single discharge, expends as great a 
weight of powder and shot as the whole broadside of a 
good-sized frigate of our own early days, does not surpass 
the gun which peeped from that frigate’s ports so much 
in size and power as in the superior scientific principles 
of its manufacture. We propose in the present article 
to give a general view of these principles. The method 
of manufacture will be first explained, and afterwards 
the principles which guide the selection of the best 
material. Although the material must be selected before 
it is manufactured, yet a knowledge of the construction of 
a heavy gun, and of the qualities sought by construction 
to be developed, will very greatly facilitate our compre- 
hension of the reasons of choice and preference among 
the many kinds of iron that might be and that are used, 
In explaining the construction of modern ordnance as 
made for the British Government, it will be best to notice 
