A joint resolution has passed both Houses of Congress relieving the Northern Pacific Railroad Company of the prohibition against mortgaging the road. This resolution was adopted in consequence of a proposition by the company to build the road withoit further Government aid, in consideration of the authority thus given to them. The Superior Gazette says an assurance has been given on the part of the company that the road will be commenced early in tJe "spring vnd pushed with a vigor worthy of so great an enterprise. Now that the tlirng begins to look like work, we lay before our readers some facts showing the advantages this route possesses over that tff the Union Pacific. The eastern terminus of this roa.8 is at Superior, situated at the western extremity of Lake Superior, and its western terminus is to be at the southern extremity of Puget Sound. Its length is 1,725 miles, of which theyournal above quoted says: " Not over 250 miles will have an elevation exceeding 3,000 feet above the sea, while of the Union and Central route, 1,100 miles are more than 4,000 feet above the sea, and more than 500 miles of it have an elevation of 7,500 feet above the ocean. Every 300 feet of ascent lowers the mercury one degree. The elevation of the valley of the Yellow Stone is scarcely above 2,000, while upon the same jaeridian the Union road reaches an elevation of 6,000 feet, and at the summit reaches 8,424, while the Northern route only attains 5,330—a difference of nearly 3,100 feet. Beside this, the fall of snow at the same elevation on the two routes is one-half less on the Northern than on the other, owing to the extreme dryness of the atmosphere. " While a large portion of the lands granted to the Northern road is susceptible of a high state of cultivation, and of sustaining a dense population, riot one acre in one hundred of the Union grant is susceptible of keeping alive more than one sage hen to the square mile. " The Northern road will cross and drain from the north of it the country to which the United Statss must look for all time to come for its supply of wheat. The country which the hardy emigrant from the north of Europe will cccupy in almost countless numbers, when this road is opened. On this route he will find his ' home' climate, and as they are the better class of immigrants will add millions to the wealth of the country through which the route passes. By the time the road reaches the mountains, at least two or three hundred thousand of population would be drawn to its line; while on the Union, except at two or three isolated spots, hardly as many hundreds have an abiding place. The arable portion of the great central plain of the American continent extends twelve hundred miles to the north and northwest of the head of iake Superior; while it does not reach over hilf that distance to the west of Chicago. The distance from the former to Lake Winnipeg is less than from Chicago to the Missouri river " The Northern route for six months in the year will not have a land carriage to exceed 1,750 miles, and from this point to the seaboard during the season of navigation, freights can be transported for one-third what railroads charge." Tne latter advantage will also enable the company to do through business for a considerable portion of the year before the road is completed, by laying sections connecting the navigable waters which, for a large portion of the route, lie almost parallel to its general course. Although this route lies so much farther north than the Union Pacific, its lower mean elevation compensates for the higher latitude in its climatic effects, and we regard it as established that there is less danger of snow obstruction than on the Union Pacific line. We have always regarded this route with favor, and are glad to see such good prospects for its speedy construction. When it is remembered that 'vessels coming from China make the North American coast near the straits of San Juan De Fuca, the entrance to Puget Sound, it will be seen that this road is destined to become, on its completion a formidable rival to the Union Pacific for the China trade. So far are we, however, from thinking either will ultimately suffer from competition, that we believe ere another half century shall have passed, the increase of population on the Pacific coast will necessitate the construction of a third trunk line connecting the great West with the Atlantic. mercury and Sulphur. A few interesting facts,in which mercury plays a remarkable part are worth mention. Certain Dutch chemists discovered that plants cannot live in an atmosphere which contains vapor of mercury. Boussingault, of Paris, found that this noxious effect could be neutralized by introducing sulphur into the atmosphere; and further, that sulphur, when exposed to vapor of mercury, takes on a coat which resembles iron, and does not easily rub off, or soil the fingers. This coat is sulphurct of mercury. Here, therefore, is a suggestion which may be turned to account by enterprising artists. Let them melt sulphur, and cast it into statuettes, friezes, moldings, flowers.and so forth, expose them to vapor of mercury, and they will ob -tain a number of articles, all wearing a metallic appearance, which may be found useful for ornamental purposes. The French chemist, taking a wide view of the subject, asks whether sulphur, which is at times found in the atmosphere, may not play an important part in neutralizing the effects of noisome vapors, or the deleterious miasm which rises from marshes and the banks of rivers in hot countries. And may we not ask, whether it will ever be found possible to stay the progress of an epidemic by flooding the atmosphere with iumea of sulphur ? Tlie Hydroscope. An Instrument called the Hydroscope has recently been invented in England, and is intended to be used for the purpose of measuring the distance of an object from a coast battery, situated at least one hundred feet above the pea level. The construction" of this instrument is described as being exceedingly simple, and the apparatus, it is asserted, can be used with great ease. The hydroscope consists of a piece of ordinary gas pipe, about six feet long, to the extremities of which upright tubes are attached. The whole is filled nearly full of water, and in each upright tube is inserted a tin float, carrying a crosspiece, and weighted so that when the long tube is in a horizontal position the cross bars are on an exact level. An upright tangent scale, graduated for yards of distance, is attached to the sight end of the tube, which moves on its center in both a horizontal and a perpendicular direction. The instrument is placed in any part of the battery which commands an open view, and the observer revolves the tube until it is in a line with the object, and then raises the tangent scale until he can just see the object in a line with the two cross bars. The range is then read off in the tangent scale, and the gun is placed in the direction thus ascertained. Well-Dikected Lieeeality.—Mr. Peter Cooper, the founder of the Cooper Union in this city, has furnished the Trustees with the sum of $20,000, to be applied to purchasing a complete s t of mechanical models, illustrating every conceivable form in which power can be applied to machinery. The models Will be procured in Darmstadt, in Germany, and will be about 2,000 in number. Proposals have been published in Berlin for the formation of a companyto lay down a new telegraph line between Europe and America, to be called the International People's Cable. One part of the arrangement is, that the subscribers are to receive bonds which will be accepted in payment for tie transmission of messages when the line is in working order, 200 Improved Steam Cooking Apparatus. It is well known that steam is a valuable agent in the cooking of food, and it is utilized, to a great extent, not only in large establishments, where food is cooked by wholesale, but in private families. The design of the apparatus shown in the accompanying engraving, is not only to afford a means for generating steam for this purpose, but to generate it rapidly and continuously, with tlie expenditure of but little f uel. The lower portion, A, is the furnace, or the compartment into which gas is introduced by the flexible pipe. The top of this department consists of a fine wire gauze, through which the gas passes and is rendered combustible by means of the oxygen of the atmosphere, that gains access through the space, B, between the gas chamber and the generator, C. The construction of this portion is peculiar. It is seen plainly near the top of the figure, where the shell is shown as broken away. The water spaces are radial, interspersed with similar radial spaces for the products of combustion, their cross-sectional area being two or three times greater than that of the water spaces. The latter communicate with a central cylindrical chamber. It will be seen that the heat entirely envelops the water, and, passing up through the interspaces, escapes, as seen, in the direction of the arrows. The relative area of heating surface, compared with the water surface, is very great, insuring a rapid boilingand a constant and eqSable heat of the fluid, notwithstanding the influx of water to supply that thrown off as steam. The water tank, or reservoir, is represented at D. This may be connected to the generator, as shown, or may be distinct and apart from it, as desired. The water passes from it to the water spaces of the generator by the pipe, E, by which the hight of water in the generator is kept always at the same hight as. that in the reservoir. The steam is delivered to the food to be cooked through the pipe, F. The principal advantages claimed for this apparatus, are the rapidity and equability of the generation of steam for cooking purposes. The heating surface, compared with the water surface, is enormous. It is evident that gas is not absolutely necessary as a fuel, as any lamp, or even charcoal, may be employed with a slight modification of the furnace portion. The inventor has, also, other arrangements of this device, adapting it on a larger scale to the generation of steam for yielding power. Patents were issued to Job A. Davis, Nov. 3, 1868, and Feb. 2, 1869 Communications and orders should be addressed to the patentee, Watertown, N. Y. Improved Three Wheeled Velocipede. An objection strenuously urged by physicians against the velocipedes, now so popular, which are driven by the feet, is that the labor demanded by the lower limbs tends to produce hernia, or rupture. We question the ground for this objection, but if any exists, the vehicle shown in the accompanying engraving obviates it, being impelled wholly by the hands and arms, the feet and legs merely guiding the machine. The front, or driving wheel, may be made of any size required, within practicable limits, that represented in the engraving being about four feet diameter, with which the inventor says he can make twenty-five miles per hour on a level. This wheel is held in the f orlft of an arched reach, the rear end of which is pivoted to an arched axle, the ends of which form journals for the two guiding wheels which are about two feet in diameter. The rider sits on a saddle connected to the reach by an upright sliding bar, and is sustained by a spiral spring to give ease of motion. Directly in front of the rider is an upright, through the crosspiece of which runs a shaft, having on each end hand cranks, from which rods run to corresponding cranks on the driving wheel shaft. These cranks are placed at right angles so that the machine, may be put in motion from a state of rest, in whatever position the cranks may be. Stirrups, in which the rider places his feet, are attached to cords that run to the rear axle and serve to guide the machine, as may be plainly seen. When the vehicle is to be run straight forward a spring fixed to the center bolt of the rear axle, that passes through the end of the reach, holds the axle in the proper position. This yields when pressure is brought to bear on the stirrups, but when the pressure on either stir-. riip is released the spring brings the axle to its normal trans-! veree position. i The inventor states his claims of superiority of his velocipede thus: Greater speed with less labor and fatigue; a more perfect control of the machine than has been obtained by others; in going down hill the speed of the machine is entirely under the control of the rider; capable of ascending steeper inclines than can be done by other machines; cannot be easily overturned and occupies less space and is lighter than others, one that he uses sustaining three hundred pounds and weighing only forty pounds, although clumsily constructed. By substituting a side saddle and shortening one of the stirrups, the vehicle may be adapted for ladies' uso without change of the ordinary costume, and is adapted equally well to children or grown people of either sex. The inventor also considers rubber tires preferable to those of unyielding iron. Patented through the Scientific American Pat- ' ent Agency, Feb. 2-3, 18G9, by Isaac Samuels, of Marysville, Kansas, who may be addressed for rights, etc., as above, or Box 773 New York city.