288 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
Sixteen caiidlepower lamps are in general use on board tbe Albatross. The copper 
wires, being of high conductivity and of ample size, carry tbe current with but little 
warming, notwitbstaudiug tbe white beat of tbe carbons in tbe circuit; by varying 
tbe size of tbe wires it will be found they follow tbe same law as to resistance and 
beating as tbe carbons. 
Let E = tbe resistance of a conductor; S = its sectional area; L = its length; 
a = constant depending on material of which tbe conductor is made; then S E = ah, 
and from this simple equation tbe relative sizes of tlie wires and carbons have been 
determined. 
Tbe “lifetime” of these lamps is warranted to be (500 burning hours. 
SAFETY CATCHES. 
In event of a “short circuit” (an accidental connecting of tbe + and — wires) 
by a good conductor there would instantly be generated sufdcieut beat in the wires 
to melt them and to set tire to tbe adjacent woodwork, and possibly melt tbe armature 
also. To prevent this, Mr. Edison has devised bis cut-out blocks and safety plugs, 
shown in tigs. 9 and 10 (plate xiii). The wires of tbe circuit connect to the binding 
screws in tbe blocks, while tbe plugs screw into tbe sockets of tbe blocks when tbe 
circuit is completed through tbo plugs, after tbe manner of tbe lamps; but tbe wire 
which connects tbe two poles of tbe plug is made of a fusible alloy, which melts at aliout 
400 degrees, and tbe melting of this wire breaks tbe circuit. When this happens all 
tbe lamps fed through that plug will go out. These safety catches are placed on the 
main wires near tbe dynamo and on every branch circuit near tbe j)oiut where tbe 
mains are tapped. 
VENTILATING. 
Natural ventilation is provided by large air-ports and skylights which, uuder ordi- 
nary conditions, afford suflicient circulation to insure normal hygienic conditions, but, 
to guard against the discomforts of closed ports and skylights in stormy weather, and 
to insure the safety of the laboratories where large quantities of intiammable material 
and volatile liquids are carried, the vessel is provided with a simple system of artiticial 
ventilation capable of supplying over 7,000 cubic feet of air per minute. 
The plant consists of a pair of Sturtevant No. 5 Monogram exhaust fans, driven 
by an upright engine belted to them. Tbe conduits are of Eoot’s spiral galvanized- 
iron pipe. Those leading forward are 9 inches and those leading aft 7 inches in diame- 
ter, both diminishing in size to 3 inches in diameter at tbe extremities of tbe ship. 
They run fore and aft on both sides just under tlie lodger plates of tbe berth deck, 
and branch pipes 3 inches in diameter are carried up through the deck to the 
apartments to be ventilated. 
Each pipe terminates in a polished brass register, easily worked by hand, and air 
and water tight when closed; sliding gates in the conduits control the volume of 
air exhausted from different compartments and shutoff communication in case of tire. 
The air is rapidly changed by running the fans even at a moderate speed, when there 
follows a notable absence of odors peculiar to ships, of stuffiness in tbe sleeping 
apartments, of headache and nausea on waking in tbe morning, and of dangerous 
accumulations of gas in tbe laboratories. 
