Dec. 1, 1903.] THE TROPICAL AGRICULTURIST. 
3?5 
And this is where the dinger cotaes in — a danger, 
however, eusily guarded against.. 
When a man grasps a conductor with hia hands and 
his feet are connected with what electricians called 
"eaiih," the othev conductor of the supply service 
being connected to ''earth" also, or when he grasps 
two conductors representing tha two Bides of the 
snpply service witli his two hands, a current passes 
through his body as long as he remains iii connection. 
This current passes through the nerves controlling two 
of the vital organs, the lungs and the heart, and the 
danger will depend on the preasure of the service, the 
strtnglh of the current which passes, and the time 
during which it passes, the last being one of the most 
important factors. Tha streugtla of the current 
passing will depend also on the pressure, and on the 
contact the victim makes with the supply service and 
with "earth." 
The blood ia forced throngh the arteries, the small 
capillaries, and the veins by the action of the heart. 
The heart is, in fact, a pump, and is subject to many 
of the laws governing other pump'. If anything 
occurs to stop or to lessen the action of the Inngs, the 
action of the heart is lessened by the increase of the 
resistance to the passage of the blood through the 
vessels, and by the decrease of energy delivered to the 
heart itself. If this goes on for any length of time the 
heart must come to rest, as any other pump would. 
And that is what takes place when an electric shock 
is received, either from hand to hand or from hand to 
feet. If the shock is very powerful the heart may stop 
at once. If it is not very powerful, but if th>^ passage 
of the current continue) for any length of time, the 
heart may cotce gradually to rest, and this is what 
seems to have taken place at Fulham and in other 
cases. 
Some Recent Accidents. — I have investigated several 
instances of death from electric shock during the past 
few yearp, wheie the pressure was supposed to be safe, 
and would have been safe with very trifling precautions. 
The conditions in all the cases were the same. 
There was an electric service of either 500 volts con- 
linnous current or 200 volts alternatinir. The victims 
in each case were making good connections wiih "earth" 
throngh their feet and other portions of their bodies. 
They made connections with a conductor in which 
there was an electric pressure by grasping another 
conductor which was in connection with the supply 
conductor, through a break in the insulating envelope. 
The connection was in nearly everv case for several 
minutes at least. At a mine in Warwickshire the 
victim was standing on wet ground, in wet boots and 
stockings, the ground being in connection with one 
side of the 500 volt continuous current supply service, 
and he made connection with the other side of the 
service by grasping an iron girder, whose edge had 
scraped its way through the insulator to the conductor. 
The current was passing for at lea«t ten minutes. 
At Sheffield the victim stood on the wet lead floor of 
a lavatory, one side of the 200 volt alternate current 
snpply service being connected to "earth," and he 
made connection with the other side of the supply 
service by grasping a brass bracket inside which the 
supply wires ran, the sharp edge of the bracket having 
been forced through the insulating envelope by the 
victim himself in pulling the bracket down. The 
current was only passing through the man's body in 
this case for a very short time. He died probably 
partly from fright, caused by the shock, and pirtly 
from concussion of the brain caused by his mate 
pulling him violently down, so that the back of his 
head struck the concrete floor. 
At Fulham the victims apparently made connection 
*o tarth through the water in the baths, and through 
the drain pipes of the bath, a large portion of their 
bodies being in direct connection with the water, 
which was warm. They made connection wi'h the 
supply service, which was at 200 volts, by grasping a 
pipe in whiph the snpply wires ran, the pipe being 
' insulated frQm " earth," but being iu connection with 
the condactor inside through some abrasion of the in- 
sulating pnvplop". The victims were in connection 
with the supply service for some minutes, during which 
the action "f ho h".ivl was gradually arrested. 
How TO Prevent Danger. — There are two method? 
of avoiding similar accidents. One is by making the 
insulation envel .pea of tha supply conductors very 
much Ptronger mechanically than is at present the 
cnstom, so that they cannot be easily cut through, 
Electricians and wiring contractors are apt to leave 
this part of the problem out of account altogether, and 
no one troubles so long as nothing happens. 
The other method is to connect all metal pipes 
tubes, brackets, etc.. through which supply wires run 
to "earth," so that no differences of pressure can 
possibly exist between them and "ear'h." 
Boihi these methods should be applied, and we should 
then hear no more of accidents of the kind, even when 
still higher pressures rule. It is the difference of 
pressure between the pipe or the bracket which is 
gra-ped and the "earth" with which the victim is in 
connection which causes the trouble If the pipe 
cannot make connection with the conductor, and if the 
pipe is at the same pressure as the earth no current 
can pass and no danger follows-— i^ortt^on Z>aj7)/ Mail 
RUBBER AND RUBBER-YIELDING PLANTS 
FROM THE FAR EAST AFRIC.l PRO- 
TECTORATE. 
These specimens were forwarded to the Imperial 
Institute by Sir C. Eliot, Commissioner of the bast 
Africa Protectorate, with a view to the chemical 
examinition and commercial valuation of the rubber 
and the botanical identitioation of the plants from 
which the rubber was obtained. In the accompanying 
letter the specimens were described as follows : — 
" A sample of the coagulated juice of a vine which 
grows in abundance in the Nandi Forest, together 
with specimens of the leaves, flowers and fruit : also 
samples of the rubber, leaves, flowers and fruit of a 
vine which grows near Tikaungu . . . Both 
plants are abundant in their respective localities." 
The specimen received were, however, more uumer- 
ous than is indicated above, and comprised : — 
1. The leaves flowers, fruit and coagulated juice 
of a vine which grows in abuiidance in the Nandi Forest, 
Mombasa. Forwarded by Mr. Mayes. 
2. Rubber from Nandi. Forwarded by Mr. Uobley. 
3. Three Rubber vines from Takiuugu, labelled 
Mbungu, Vipo and Impira respectively. 
4. A euphorbiaceous rubber plant from Takaungu. 
5. Rubber from Tukauugu, 
The botanical specimens have been identified for 
this department at Kew by Dr. Otto Stapf, who 
reports that the vine from the Nandi Forest is 
Landolphia TVatsoniana. Voigtherr ; the vines from 
Takaungu, labelled Mbungu and Vipo, prove to be 
the same species, viz , Landolphia Petersiana, 
Dyer; the vine from Tokanngu, labelled Impira 
(also known as M'pira) is Landolphia Eirhii, Dyer ; 
and the enphorbiaceons plant from Tiikaongu is 
Manihot Glazioui, Muell-Arg., a native of Brazil. It 
may be noted here that the ''Jlbnngu" rubber of 
Bast and West Africa is usually stated to be obtained 
from Landolphia florida, whereas the plint from 
Takaungu kuown by this name is Landdolphia Feter- 
siana, 
01 the three samples of rubber accompanying the 
botanical specimens, two were forwarded from Nandi; 
one of these being derived from the vine which 
has been identified as Landolphia Watsoniana. 
whilst the botanical source oi the other is not stated 
In the case of the sample of rubber fi'om Takaungu 
no indication is given as to the particular plant 
from which it was obtained. 
DESCRIPTION OF THE SPECIMENS. 
1. Rubber Irom Nandi, forwarded by Mr, Mayesi 
Derived from Landolphia Watsoniana, 
