OCTOBER 30, 1902] NATURE 657 
| 
eae Limit of Breaki 
Aluminium. Principal Impurity. Other impurities. oe oe blastic: ve Toad 
995 percent. | Commercial aluminium Fe (0°31), Si (0°14) 2°715 61°5 19,376 _ | 28,200 
98-97 ee | Copper, 1°6-2°6 percent. Fe (0°4), Si (0°4) 2°75 51 33,000 | 41,000 
98-97 3 Zinc, 1°2-2°4 A Fe (074), Si (0°43), Cu (02) 2°74 | 56 20,500 28,000 
98-96, Nickel, 1°2-2°2 ,, Fe (0°6), Si (0°35), Cu (o'r) | -2°745 2°5 22,000 36,000 
98°3 ' Iron, 1°2 3 Si (0°4), Cu (o'r 278 S71 20, 300 31,300 
C , oe oe ay * (ean - ; 
97 i Hees oe # \ Fe (0°43), Si (0°37) 2°75 49°7 36,600 45,900 
Hard drawn copper ... 8-9 98 28,000 64,000 
and strength of this alloy enabling spans of 150 feet to be 
made with safety. A great saving in the number of poles 
is thus effected, which is one of the principal advantages 
gained. Numerous other important transmission schemes 
might be quoted in which aluminium is used, or in which 
it has been decided to useit. As has been just pointed 
out, the use of aluminium effects a great saving in the 
number of poles required ; it also involves dealing with 
a much smaller weight of conductor, and is, finally, 
cheaper than copper. In round numbers, for equal 
conductivity, the section of an aluminium cable is one | 
and a half times that of a copper one, the weight is half 
and the tensile strength three-quarters. It is the 
decreased weight which, in spite of the smaller tensile 
strength, allows longer spans to be used, and this effect 
can be made more marked by the use of a suitable alloy 
possessing increased strength without much diminished 
conductivity or much higherspecific gravity. Mr. Morrison 
gives an interesting table showing the variation, accord- 
ing to the price of copper, in the price per lb. that can be 
paid for aluminium for equal conductivity and equal cost. 
From this it appears that with copper at its present price 
of about tenpence per Ib., twenty-one pence per lb. could 
be paid for aluminium, which is two or three pence above 
its market price, showing that aluminium conductors are 
cheaper. 
It is to be noted that the above remarks apply only to 
bare conductors. Where insulated cables are needed for 
low-tension work the increased diameter of an aluminium 
conductor involves increased cost in insulating material ; 
moreover, with lead-covered cables the increased weight 
of the lead would almost, if not quite, cancel the decrease 
in weight gained by substituting aluminium for copper. 
For high-tension cables it is possible that aluminium 
may in some cases be cheaper than copper. Thus ina 
paper by Mr. M. O’Gorman! it is shown that increasing 
the diameter of the conductor may produce such a 
diminution in the depth of insulation necessary as to 
lessen the total price ; in such circumstances a tubular 
copper conductor, or an aluminium conductor, could be 
used with advantage. There seems, therefore, a possi- 
bility that aluminium may some day successfully invade 
the field of insulated cables, hitherto regarded as pecu- 
liarly the property of copper. MM: S. 
RECENT WORKS ON SYSTEMATIC BOTANY 
IN GERMANY. 
3 
was in the year 1887 that, following on the publisher’s 
announcement, the first parts of “Die natiirlichen 
Pflanzenfamilien” appeared under the joint editorship of 
Drs. Engler and Prantl. The announcement does not 
seem to have attracted much attention, as there was no 
mention of it in many botanical journals until several 
numbers following each other rapidly came under notice. 
Strange as it may seem, De Bary’s name does not appear 
as one of the collaborators, nor did he have any share in 
1 ‘“‘ Insulation on Cables," by Mervyn. O'Gorman. (Journal of the 
Institution of Electrical Engineers, vol. xxv. p. 608.) 
0. 1722, VOL. 66] 
the work. His remarks, therefore, as set forth in Dée 
Botanische Zeitung in October, 1887, besides providing a 
criticism of the general scheme, also enable one to form an 
idea of the attitude displayed towards the undertaking. 
He says, “the object is to present by means of illus- 
trations and descriptions a corporate picture of the plant 
world which shall be strictly scientific and at the same 
time generally intelligible. Under each family, and for 
each genus of that family, mention will be made of any 
points. that call for description or that have a practical 
bearing.” 
That there was some uncertainty as to its successful 
completion may be gathered from what he says later, 
after congratulating editor and publisher :— 
“Tf the book is only carried through as it has been 
started, then it will have no equal . . . since it gives in- 
formation shortly and objectively, not in the abstruse and 
learned manner of Bentham and Hooker, nor yet in the 
form of the subjectively learned monograph touched up 
with popular varnish which characterises the otherwise 
life-like history of plants by Baillon.’ Undoubtedly the 
terse and vigorous descriptions, the careful choice of 
matter,.and the wealth of illustration which elicited 
favourable comment for the earlier numbers have, on the 
| whole, been consistently maintained. Now that the work 
is almost completed, and as one looks back on the enor- 
mous labour entailed, congratulations may again be 
offered to Dr. Engler, who has been the sole editor since 
Dr. Prantl died in 1893. 
The responsibility of such a vast undertaking might 
well be sufficient, but in the year 1900 Dr. Engler an- 
nounced the publication of a new work, ‘‘ Das Pflanzen- 
reich””—adopting the title suggested by De Bary—which 
will amplify the information given in “ Die natiirlichen 
Pflanzenfamilien.” As Dr. Engler announces in his in- 
troduction, “Das Pflanzenreich” is not a revised edition 
of ‘‘ Die natiirlichen Pflanzenfamilien,” for appendices 
to the latter will continue to appear from time to time, 
and whereas ‘‘ Die Pflanzenfamilien” gives a complete 
account of the orders and genera, but only enumerates a 
few species, “ Das Pflanzenreich” will furnish a full and 
comparative account of all authenticated species. 
Eleven parts have already been issued —“ Musaceze,” 
by K. Schumann ; “Typhaceze and Sparganiacez,” by 
P. Graebner ; “ Pandanacez, ” by O. Warburg ; “ Moni- 
miacez,” by J. Perkins and E. Gilg ; ‘‘ Rafflesiaceze and 
Hydnoracez,” by H. Graf zu Solms Laubach ; “Sym- 
plocaceze,” by A. Brand ; “ Naiadacez,’ by A. B.-Rendle ; 
“ Aceracez,” by F. Pax; ‘“‘ Myrsinacee,” by C. Mez ; 
“ Tropzolacez,” by Fr. Buchenau ; and “ Marantacez,” 
by K. Schumann. 
As regards the general arrangement, the citation of 
important literature and the review of the main characters 
of the order are similar to the method adopted in “ Die 
Pflanzenfamilien,” and, together with a certain number of 
illustrations, will be more or less the same. But, apart 
from new facts which may be added, it will be observed 
that the orders are not necessarily taken up by the same 
authors in the two works, English botanists may be 
