156 Notes and Comments. [J. F. I.,

country of the invent ions of citizens of the other. The Japanese pa tents are grau ted for any one of th ree terms, namely, five, ten or fifteen ) ears, reck- oned from the date of registrat ion, these te rms not be ing al terable after the pa tent has been grauted. Designers of improvements on pa tented invent ions are required to obtain a license from the patentee of the or iginal invent ion before applying for a pa ten t upon the improvement . I f th is l icense to use the original invent ion cannot be obtained, the Minis ter of State may gran t the patent , fixing the compensat ion to be paid to the original patentee. No an- nuit ies are required, bu t pa tents shal l be forfeited when the patentee, wi thout sufficient reason, has not exploi ted his invent ion wi th in three years of the date of his patent , or discont inues working the invent ion for three years at any time, or when the pa tentee imports and sells an article for which he has ob- ta ined a patent , or acquiesces in the sell ing of an article which infr inges his rights. Inf r ingers of pa ten t r ights are l iable for damages to the patentee, the te rm of l iabil i ty be ing th ree years.--Electrical World.

T H E CARBON D I O X I D E M o T o R .

At the stated mee t ing of the F rank l in Ins t i tu te held April 2oth, Mr. Win. F. Roberts described and exhib i ted in operat ion an engine devised by him, which is actuated by carbon dioxide.

The engine exhib i ted was a t r iple cyl inder machine, 2-inch bore and 2-inch stroke, double acting. I t was shown in bo th vert ical and horizontal types. In the horizontal engine the bed-plate is 24 x I4 inches ; and in the vert ical form I4 x IO inches ; he ight , 18 inches. The power is t ransmi t ted from bo th ends of crank-shaft .

The cyl inders are fitted wi th positive, automat ic cut-off valves, operated by a cam mechanism and cu t t ing off at one sixty-fourth of an inch. The claim is made tha t the eng ine is capable of r u n n i n g at 2,ooo revolut ions per minu te under a pressure of 1,5oo pounds per square inch, and of developing under those condi t ions twenty-five horse-power. The total weight of this horizontal form of engine, inc luding bed-plate, is eighty-five pounds.

The engine is supplied with gas from steel cyl inders con ta in ing the carbon dioxide in the liquefied state, communica t ion wi th the cylinders be ing estab- l ished th rough a small copper pipe coiled in the form of a hel ix. In th is hel ix the gas is hea ted unt i l the desired pressure is obtained. A very large re tu rn is claimed. \V.

T H E A L U M I N U M INDUSTRY.

From London Engineering we learn tha t the present output of a luminum in the world is a l i t t le less t han io tons a day, of which about one-fifth is produced in the Uni ted States. In Great Britain, the British Aluminum Com- pany has its works, at the Fal ls of Foyers, in full operation, using about 3,5oo horse-power for the product ion of calcium carbide and a luminum, and mak ing about 6,0oo pounds of the la t ter a day. This company is mak ing preparat ions for a very much larger output. In France the Soci6td Electro-MetaUurgique Fran~aise, at Le Praz, makes 3,6oo pounds a day with 3,ooo horse-power by the Heroul t process, and the Soci~t6 Industr ie l le d 'A lumin ium at St. Michel