The use of the air method of propulsion did away with the necessity of a large propellor such as most airships have to use, a propellor which must of necessity be very light and which is easily broken.

Next to the engine room was the kitchen.  It contained an electric range and all necessary appliances and utensils for preparing meals.  There were lockers and a large reserve storeroom which when the time came would be well stocked with food.  Forward of the kitchen was the living and dining room.  It contained comfortable seats, folding tables and a small library.  Here, also were many instruments designed to show how the various machines were working.  There were gages, pointers and dials, which told the direction the ship was traveling, the speed and the distance above the earth or below the surface.  Similar indicators were in the conning tower, which had a powerful search light.

The ship was lighted throughout by incandescent lamps, and there was even a small automatic piano worked by the electric current, on which popular airs could be played.

If the gas and the gravity neutralizer worked as Professor Henderson hoped they would, as soon as the ship was completed, all that would be necessary to start on the voyage would be to fill the aluminum bag and set the air compressor in motion.

The gas was made from common air, chemically treated and with a secret material added which by means of a complicated machine in a measure did away with the downward pull of the earth.  Thus all that was necessary to carry on a long voyage was a quantity of gasolene to operate the engine which worked the electric machines, and some of this secret compound.

The professor and his helpers had been working to good advantage.  At last all was in readiness for the gas test.

It was proposed to try it on an experimental scale.  Some of the fluid was to be generated and forced into an aluminum cylinder under the same pressure it would be used in the air ship.  To this cylinder were attached weights in proportion to the weight of the Flying Mermaid with its load of human freight, engines and equipment.

“This cylinder is just one one-hundredth the size of the cylinder of the ship,” said the professor.  “I am going to fasten to it a hundred pound weight.  If it lifts that our latest contrivance will be a success.”

“You mean if the little cylinder pulls a hundred pounds up the big ship will take us and the machinery up?” asked Mark.

“Certainly,” answered the professor.  “If this cylinder lifts a hundred pounds, one a hundred times as big (as that of the Mermaid is), will lift a hundred times as much, or ten thousand pounds.  That is five tons, or more than a ton over what I figure to be the weight of our ship and contents.  The latest war balloon can lift one ton with ease, and if my machine can not do five times as well I shall be disappointed.”

The last adjustments were made, pipes were run from the gas generator to the cylinder, and the hundred pound weight was attached.