AucusT 31, 1899] 
NATURE 
427 
production, not of rubber, but of colophene—a thick sticky oil, 
quite useless for all the purposes to which rubber is applied. 
The Aulleten publishes correspondence showing how the falling 
off in the production of rubber at Lagos is due to the reckless 
way in which the trees have been exhausted. The rubber is 
collected from the Ire tree (Avch.xza africana), and has been an 
important source of wealth to the Colony ; but the industry is 
rapidly decreasing, owing to want of control over the collectors 
who tap young trees, and destroy rubber forests by over-working. 
In Madagascar efforts are now being made to establish plant- 
ations of rubber-producing plants. The island has long been 
known to furnish a supply of india-rubber to commerce, the 
rubber being obtained until a few years ago from species of 
Landolphia—the rubber-vines, which are so widely distributed 
in tropical Africa. About 1892 another source of rubber was 
exploited, but unfortunately both the trees and shrubs producing 
rubber have been ruthlessly destroyed, and it is necessary to 
take active steps to cultivate rubber plants to preserve the 
industry. The May and June Avc//ed2 contains correspondence 
which indicates the actual source of Peruvian india-rubber. 
According to the information received, the Caucho tree of 
Peru is a Castilloa. 
Bulletin, No. 56 (April 1899), of the West Virginia Agri- 
cultural Experiment Station, Morgantown, consists of a report 
on investigations to determine the cause of unhealthy conditions 
of the spruce and pine from 1880-1893. This is one of 
the admirable series of reports which are now issued regularly 
in many parts of the United States, in order to cope with the 
immense destruction wrought by insects in that country, 
resulting, during the fourteen years mentioned above, ‘‘ in 
the death and total loss of many hundred thousand dollars’ 
worth of the finest timber in the State” of Virginia. Ento- 
mology is no child’s play in the States, and Prof. Hopkins 
enumerates 197 species of insects, observed by himself as infest- 
ing the spruce and pine, about half of which are injurious, the 
remainder being beneficial as parasites of the destroyers, or in- 
different. These belong to all orders of insects except Orthoptera, 
and we imagine that a careful search would be able to fill up this 
gap by the discovery of some Blattidve, at least, under loose bark, 
or in similar situations. Most of the mischief, however, is done by 
wood-boring beetles, of which, and of their curious burrows, 
many illustrations are given, There is also an illustration of a 
portion of a black spruce tree eight inches in diameter, which 
had been slightly injured, when a colony of large black ants 
(Camponotus pennsylvanicus) took possession, and hollowed 
out the trunk till the heart-wood was completely destroyed, and 
the tree fell. This report should be of great interest both to 
entomologists and foresters, for our own conifers are liable to 
the attacks of a large number of insects congeneric with many of 
those here mentioned, though others (as for instance Camponotus, 
just referred to) do not inhabit this country. 
In the U.S. Monthly Weather Review for May, there is a 
useful summary of the climatology of the Isthmus of Panama, 
by Brigadier-General H. J. Abbot. The first Panama Canal 
Company made daily observations at Colon, Gamboa and Naos 
during the years 1882-7, from which it is seen that the temper- 
ature differs very slightly during the year. At Colon the mean 
of the absolute maximum temperature varies from 89°°6 in 
February to 91°°9 in October; and the absolute minima from 
68°-4 in January and April to 70°*5 in October. At Gamboa the 
absolute mean maximum was 97°'5 in June, and the minimum 
59°°4 in February ; and at Naos these means were respectively 
96-3 in June and 66°°7 in March. Throughout the whole 
Isthmus the rainy season begins with May ; owing to the north- 
ward advance of the layer of rising air, a diminution takes place 
in July, in the interior, but is subject to the delay of one month 
NO. 1557, VOL. 60] 
on the Pacific side and of two months on the Atlantic side. A 
second maximum occurs at the end of September in the interior, 
but at the end of October on the Pacific coast and in the middle 
of November on the Atlantic coast. Then comes the dry 
season, which begins everywhere about January 1, and continues 
for four months. The mean annual rainfall is 120 inches on 
the Atlantic coast, 93 inches in the interior, and 62 inches on 
the Pacific coast. Although the rainfall is large, it is com- 
parable with the amounts registered in the United States near 
the Gulf of Mexico. The paper contains a number of frag- 
mentary observations referring to other periods, for which hourly 
or monthly variations from mean values have been calculated. 
WE have received from the Observatory of Manila, of which 
the director is Father J. Algué, S.J., a volume (pp. xvi + 192, 
4to) entitled ‘*Las nubes en el Archipiélago Filipino.” The 
observatory was one of the institutions invited by the Inter- 
national Meteorological Committee to take part in the special 
observation of clouds during a year ending May 1897. The 
volume in question, owing to delay in preparation of the 
necessary instruments, contains results from June 1, 1896, to 
July 31, 1897. The work is divided into two parts, giving (1) 
an account of the principal nephoscopes and theodolites in use, 
and the results obtained in the Philippine Islands by means of 
some of them; and (2) an explanation of the methods used in 
the photogrammetric measurements of the heights and velocities 
of the clouds, and the valuable results obtained at the Manila 
Observatory. The volume also contains an interesting account 
of the importance of the observation of the movements of upper 
clouds for the purpose of storm prediction. 
THE ‘‘Eight Queens Problem” is the problem of finding 
the different ways in which eight queens might be arranged 
on a chess-board so that no two should be in check of 
each other ; in other words, the number of ways of arranging 
eight pieces so that no two shall be in the same row, 
column, or line parallel to a diagonal. This problem, 
which has occupied the attention of Nauck, Gauss, Giinther, 
Glaisher, Rouse Ball, and Pein, forms the subject of a paper 
by Dr. T. B. Sprague in the Proceedings of the Edinburgh 
Mathematical Society. There are ninety-two solutions, but 
these are not all independent, for in general each solution gives 
rise to four altogether by simply rotating the board, and this 
number is doubled by taking the reflections of these in a mirror, 
the exception to this rule being when the pieces are symmetrical 
about the centre. Mr. Sprague considers the general problem 
for a board of 2° squares. This problem was reduced to one in 
determinants by Giinther and Glaisher, thus: if a determinant 
is constructed in which terms in lines parallel to one diagonal 
are represented by the same letter, and those in lines parallel to 
the other have the same suffix, the solutions are the terms of the 
determinant in which no letter or suffix occurs twice. The 
solutions for squares with one to ten squares in a side were 
given by Pein, and the ten-sided square possesses 724 solutions. 
Mr. Sprague has now given the solutions for an eleven-sided 
square, which are 2680 in number, but he considers it would be 
necessary to obtain the co-operation of a number of persons in 
order to classify the solutions for larger squares. 
Very little has hitherto been recorded in regard to the life- 
history of those peculiar North American rodents locally known 
as Sewellels, and scientifically as Hap/oéonr. It is therefore 
satisfactory to have a description of the habits and environment 
of one of the species, from the pen of such an accurate observer 
as Dr. D. G. Elliot, in the March issue of the Pudlications of 
the Field Columbian Museum. The Sewellels, which constitute 
a somewhat isolated family by themselves, are animals of the 
size of a small rabbit, but with a more beaver-like appearance 
