268 
NATURE 
[JANUARY 21, 1897 
dynasty, about B.c. 1100. The nations discussed in the 
earlier volume were comparatively few, but when we turn 
to the later one we see that it treats of the history of all ; 
the peoples who lived in the countries which lie between 
Elam on the east, Cyprus on the west, Armenia on the 
north, and Berber on the south. How they arose, gained 
power, made war and invaded each other's territories, 
attained the zenith of their glory, were conquered, and 
were finally destroyed or merged in the ascending 
might of their neighbours, M. Maspero has undertaken 
to tell; and we think that he has carried out his task 
very fairly well. The overwhelming mass of notes and 
references to authorities testify to immense energy, and 
to a desire to put the reader in possession of a large 
number of facts. In the course of his work he has 
touched upon a variety of “burning questions,” such as 
the Hyksos, the Hittites, the Exodus, &c., and we are 
tolerably certain that he will not please every one who 
reads his book; on many points we ourselves should 
disagree with him. To discuss these differences would 
require more space than we are allotted, and it is only 
fair to say that the general plan of the work is excellent, 
and that the author has spared no pains to make it a 
useful guide to the knowledge of Oriental history. On 
certain subjects his information is not obtained at first 
hand, but when we consider that he has to deal with 
Egyptians, Babylonians, Assyrians, Cosseans, Kassites, 
Elamites, Hittites, Arameans, Syrians, Hebrews, and 
others, this cannot be wondered at ; and that he should 
be led away, at times, by his authorities is quite excusable. 
His chapters on Egyptian history are, as might be ex- 
pected, worthy of his reputation. 
The Camera and the Pen. By T. C. Hepworth, F.C.S. 
Pp. 64. (Bradford: Percy Lund, Humphries, and Co. 
Ltd., 1896.) 
RELIEF blocks produced without the aid of the engraver 
are now extremely common—rarely do blocks of any 
other kind appear in NATURE—yet it is astonishing how 
very hazy are the ideas which the majority of people 
have as to the way they are made. In this slender 
volume will be found a sketch of the methods employed 
to produce line blocks and half-tone blocks, and we trust 
it will be widely read; for a knowledge of the possi- 
bilities of process work would often save the production 
of a bad block. The simplest form of process block is 
that made from line drawings, or pen-and-ink sketches. 
To obtain the best effect, the drawing should be made on 
Bristol board, or similar white surface, in very black ink. 
Liquid india ink is commonly used, but Stephens’ ebony 
stain is sometimes preferred. This is photographed by 
the process worker, and, by a simple arrangement, a 
reversed negative is obtained. A sheet of zinc, covered 
with a substance which becomes insoluble after exposure 
to light, is placed in contact with this negative, and after- 
wards the unaltered parts are washed or rubbed off. 
The zinc plate thus marked is then etched, and even- 
tually mounted on wood ready for the printing machine. 
It will be evident, then, that drawings to be used for the 
production of blocks in this way should be very distinct, 
and no lines or marks should be upon them but what are 
required to appear in the figure. The half-tone process 
is used for the reproduction of pictures other than 
line drawings. For illustrations of natural things and 
phenomena, where accuracy is all-important, reproduc- 
tion by photographic process may be said to be essential. 
The only conditions for satisfactory results are clear 
pictures, which may be either negatives or positives. 
Many hints of interest to photographers, as well as 
very instructive information on the processes of manufac- 
turing blocks for illustration purposes, will be found in 
Mr. Hepworth’s book. The only complaint which is 
likely to be raised about the contents is that they are 
deficient in details. 
NO. 1421, VOL. 55] 
LETTERS TO THE EDITOR. 
(Zhe Editor does not hold himself responsible for opinions ex- 
pressed by his correspondents. Neither can he undertake 
to return, or to correspond with the writers of, rejected 
manuscripts intended for this or any other part of NATuRE. 
No notice ts taken of anonymous communications. | 
Bog Slides and Debacles. 
THESE slides have been brought very prominently forward 
on account of the recent debacle near Gneevegullia, Co. Kerry. 
They are a subject that ought to be known and understood, as 
numerous observers and writers have brought the subject before 
the public since Gerrard Boate wrote on bogs in A.D, 1652, up 
to the present time. 
If, however, we are to judge from what has been lately 
written, the public seem to be supposed to consider such a slide 
as that in Kerry as something quite out of the common, which 
no one can understand. But, on the contrary, bog slides and 
debacles are one of the numerous Irish disturbances, that lie 
dormant for a time and burst forth suddenly when least expected 
—take Gneevegullia Bog as an illustration. It is situated on 
the watershed of the Brown Flesk, a tributary of the Maine, the 
Blackwater and the Flesk, into all which rivers at times it sent 
squirts, but especially in late years, into the Quagmire River, 
a tributary of the Flesk. Into the latter river it sent a consider- 
able squirt three or four years ago ; now it breaks forth into 
the Flesk instead of the Brown Flesk ; where it was always 
expected to go. 
Small slides and debacles of both bogs and drifts, in the Irish 
hill groups, are not uncommon, and any frequenter of the hills 
must at some time or another have seen one. They give the 
observer a very nasty sensation. Suddenly he sees a curious 
shiver in a bog flat; at first he considers it to be only the 
shimmery air over the bog, so usual in hot weather, but presently 
he sees a ‘‘ creeping where no life is seen,” with a black steam 
or sheet issuing from it. Ten to one he immediately jumps up 
to make sure that his seat has not also taken to walking. Most 
bog slides are hard to see, as they usually take place during the 
night; there are, however, exceptions to this general rule, as 
the famous slide in the Ballykillim Bog, near Clara (1825), took 
place while the turf-cutters were at their dinner, and the slide 
on March 28, 1745, near Dunmore, Co. Galway, also took 
place in the day-time, and the turf-cutters had to run for their 
lives. 
In the annals of the Four Masters there are records that 
myst refer to either water-spouts or bog debacles, but they are 
too vague to quote. Gerrard Boate, in 1652, tells us how to 
drain a ‘‘ shaking bog,” but he does not record any movements. 
The first I know of is the communication to the Royal Society 
in 1697, by W. Molyneux, of the Bog of Kapanihan, Co. Limerick, 
near Charleville. As this began at 7 p.m. on June 7, 1697, 
the first movement of this bog could be described ; afterwards 
he gives the final results, and the causes that made the move- 
ments. The newspaper reports at the time talk of the accom- 
panying great noise ; Molyneux, however, says there was none. 
The Bishop of Clogher also gives a good scientific account of a bog 
movement near Clogher on March 10, 1712 ; but the majority of 
the other records are by men who have gone in for sensation. 
This has been the case in the recent reports. No one knows 
when the movement began in the Gneevegullia Bog, but now we 
are told it was heralded in by noises and great shaking. 
The printed records of big slides or debacles that I have read 
(as far as I can remember) are the following :— 
1607. June 7. Kilpaniham, near Charleville, Co. Limerick. 
1708. Castlegarde, Co. Limerick. 
1712. March 10, Near Clogher. 
according to tradition, before 1640. 
1745. March 28. Addergot, near Dunmore, Co, Galway. 
1780. Monabogh, Dundrum, Co. Tipperary. 
1819. Valley of the Owenmore, Erris, Co. Mayo. 
1821. Slip in Joyce County, Co. Galway. 
1824. December 22. Ballyroindallow Bog, near Coleraine. 
1825 (?). Kilmalady Bog, near Clara, King’s Co. Fasset Bog, 
16 miles away, also moved, but did not burst forth, 
1867. Glen Castle Hills, Belmullet, Erris, Co. Mayo. 
1871 (?). In the Valley of the Suck, alongside one of the 
Roscommon tributaries. 
1871 (?). Clonagill, near Birr, King’s Co. , 
Other big slides will be found recorded by Lewis, but it would 
take time to go over all his County histories. 
This bog had also moved, 
