The Jenks Ship Building Co. is building for the US Lake Survey seven catamarans, each 40 feet in width. Each catamaran has two large steel cylinders 30 feet long and 40 inches in diameter. When completed, all will be fastened together and the entire width will be 280 feet. They are being put together above the Grand Trunk Railway bridge. Each of the cylinders weighs about one ton and the combined catamarans will be used for sweeping the river to ascertain obstructions to navigation. Bars of iron will be let down as a certain distance apart. Each bar will be surmounted with a flag. As the sweeping process takes place, the flags will dip whenever an obstruction is found. It is expected that the seven catamarans will be joined together and completed some time during the month of June. They will be taken out of the river sideways. A tug will be used in propelling them when in service.