and freight, and they are a medium by which plague is distributed around the world. The flea transmits the plague bacillus from one rat to another and from the rat to man. It does this by its bite. Vessels should be kept as free from rats as possible. Surgeon Cofer recommends that the following antirat measures be observed by ship captains:

(a) Destruction of rats on vessels.

(b) Prevention of rats boarding vessels.

To effect the destruction of rats on vessels the latter should be fumigated three or four times a year by sulphur burned in pots.

Almost any kind or size of iron pot will answer the purpose. The ordinary sugar pan 2 feet in diameter is useful in disinfecting the hold of a vessel or a large compartment, the number of pans to be determined by the number of thousand cubic feet of area to be fumigated. Not more than 30 pounds of sulphur should be placed in each pot. For the fumigation of staterooms and the like the small iron cooking vessels are suitable. Each pot should always be placed in a tub of water, as shown in figure 12.

The tubs should be made of wood or compressed paper, as tubs made of galvanized iron or composition metal go to pieces rapidly through rust or breaks in the seams. The pots should never be placed on the floor of a compartment or bottom of a hold of a vessel. In compartments or storerooms they should be placed upon tables or chairs, and in the holds of vessels either on the "tween " decks, upon piles of ballast, or upon boxes. The sulphur should always be ground or mashed into a powder before being placed in the pots, and should be piled around the sides of the pot with a central depression or crater. Alcohol should always be used for lighting sulphur, although a hot coal will answer the purpose.

One pound of sulphur burned in a space containing 1,000 cubic feet will produce 1 per cent of the gas. Five pounds of sulphur burned in a space containing 1,000 cubic feet will produce 5 per cent of the gas.

On empty vessels burn 2 pounds of sulphur for every 1,000 cubic feet of space and let the gas stand for six hours.

In computing the capacity of the hold of a vessel for the purpose of determining the number of thousand cubic feet of space therein, and therefore the number of pounds of sulphur which will be required to produce a 2 per cent volume of the gas, the net tonnage of the vessel shows in a general way the cubic capacity of her cargo-carrying space. Ten net tons will represent 1,000 cubic feet of space; therefore for every 10 net tons 2 pounds of sulphur must be used to get the average 2 per cent volume strength of sulphur gas. The capacity of the living apartments, storerooms, and the like had best be figured on separately.

In fumigating with sulphur gas all spaces must be made air-tight. In fumigating the holds of vessels the hatches should be covered with their regular waterproof tarpaulins and tightly battened down, leaving a small vent for the escape of the sulphur. All air slits, scuttles, and chain ports should be closed. The doors should be sealed by means of strips of paper pasted over the cracks left between the frame and the door.

If the vessel has cargo the killing of rats should be carried out under the direction of the nearest quarantine officer. After the fumigation is over the rats should be gathered (with the hands protected by heavy gloves) and burned in the ship's furnace or donkey-boiler fire-box, not in the galley.

129054-196

A RAT GUARD FOR SHIPS LINES

Now, the important thing is to keep the vessel from becoming reinfested with rats. This is effected by (1) the use of rat funnels or guards on all lines while

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the vessel is in port, (2) by keeping a watch for rats attempting to walk up the gangplank, (3) by keeping a sharp lookout for rats being concealed in loosely crated freight, (4) by keeping the ships' food and stores carefully protected from rats, (5) by distributing rat poison (phosphorus or arsenic paste) in the vessel, (6) by keeping ship's cats (they should not be overfed, else they will not try to catch rats), and, finally, by keeping rat traps constantly set. The following illustration shows what a rat guard looks like:

arms

The special points of this rat guard are these: A single shield in two parts, with (funnels) from both sides. It is hinged by bolting at the outside of the shield. There is a guide permitting a perfect fit of the two parts of the disk when closed. It can be used on many different sizes of rope, and when placed on the line fits closely by tying on both sides. Rivets are used throughout, thus increasing the strength. The outside half of the arms is cut lengthwise into three strips so that they may be bent to come into immediate contact with the rope when tied.

The details for making the rat guard are as follows: Flat sheet galvanized iron is used for all parts of the guard; 20 to 24 gauge answers best, for that weight of iron is strong enough and does not make the guard too heavy. The shield should not be less than 3 feet in diameter. The funnel tubes should be 18 inches long on each side of the shield. The central opening can be made to fit any

size of rope. One made for a 3-inch diameter rope will serve for all smaller sizes. When made or used for encircling a number of lines at the same time, the shield should be 4 feet in diameter and the funnel tube enlarged and supported by five flanges and five rivets instead of three. The guide piece, which is the one important feature of this rat guard, is riveted on one side only and then bent around the circumference. The rivets which fasten the funnel tubes go through the tube flanges on each side of the shield. One bolt, two washers, and five rivets are needed for each guard. When badly damaged by use or carelessness, a block of wood and a hammer are all that is required to restore the guard to its former usefulness.

When a ship is in port, especially in a plague-infected port, all gangways should be hoisted at night. The captain of a vessel should insist upon the repeated distribution of rat poison in the warehouses from which his cargo is to be taken. He should in some manner be able to inspect the freight intended for his vessel to guard against rats being taken aboard with loosely crated freight. By loosely crated freight is meant such articles as crockery or china packed in straw or excelsior or furniture or matting wrapped in gunny and loosely crated, also peanuts, rice, sugar, wheat, corn, oats, etc., shipped in bags.

Wherever ships go-plague will go. No rats-no plague.