| Show 7 77 4 V t 1 f wr R POPULAR SCIENCE handy electric time switch for automatically turning off and on oil at predetermined times one or more electric lights in a building the aid of an attendant it a new mechanism has been designed chere Is a dial on the face of a clock like ar ran gement and on an extension of the shaft which carries the single hand two disks are mounted with slots cut from th tho center of the these disks are held in place I 1 y trie fric tion and can be set to throw the switch at any desired hour by simply them with the hand As the klaft revolves it carries the disks with it and when the slot in the first disk a vertical position below the shaft it allows a pin which has been traveling ng on the circumference to rise to the turns the light off and on auto automat matl ca cally ily center with the res result alt that a pivoted lever on which the pin Is mounted tilts and drops a weight to pull the switch open when the second disk has reached the same position a sec see ond weight drops with a reverse et ef feet t the largest bridges the brooklyn suspension bridge 1 feet long is still the largest suspension bridge in the world the new east river bridge has a span of 1600 feest and its capacity is far greater than that of the brooklyn bridge each of its four cables has a safe strength of over 10 pounds in tension the washington bridge over the harlem river consists of two spans of feet in the clear the roebling suspension bridge at niagara was replaced in 1897 ly uy a spandrel braced two hinged steel aich of feet span it accomma dates the railway tracks on the upper deck and a highway below the tho sec see ond niagara bridge replaced the clif ton sus suspension bridge in 1898 aalde as its span is feet it is the lier gest arch of any type in hi the world in 1901 the pennsylvania railroad built a stone bridge consisting of forty eight segmental arches ot of sev enty feet span over the river it accommodates four tracks and cost about 1000 bu the cost of maintaining it is very small the address of prof jacoby of lornell university from which these figures are taken should be referred 0 o by all interested and who Is na v 9 in recent progress of the sort ft it ie in printed in science of july 4 destroys burrowing Ani animals mati there Is considerable difficulty in reaching rats mice and other pests which secrete themselves in holes in buildings or in the ground and unless they can be induced to entrap them selves they are generally permitted free range without further extort to exterminate them in the di awing here shown Is a simple device which will probably aid greatly in the work of destroying burrowing animals as it enables the operator to reaca the rodent even when lodged in tha tb deep est st part of its hole the apparatus consists of ft a fuel hamber chamber in which charcoal or home jome ther other substance which will give giva off noxious fumes is placed together with a i compression cylinder and plunger fhe the two parts of the device are located on a common base and are connected by a tube leading from the ottom bottom of the compressor to the top of the fuel holder to put the ex ator in action a fire Is kindled in the perforated receptacle provided for that purpose when the depression of the plunger will force the air from the compressor into the top ol 01 the appo r 0 pumps noxious gas into the holes site chamber causing it to pass over the coals and drive the fumes out through the pipe and into the burrow after continuing the operation for a short time the animal will be either suffocated or will make his appear ance at the mouth of the hole when it can be dispatched with a gun dog or other method as preferred the in venter Is lorenz N cornett of nativi dad cal pollution of ajr jr in ati C t i the question of the the air in large centers of on n Is coming ta be cor atad u ly as is that of pure atei ahei j ana and the removal of sergt so much of the pollution as is s due to dust and emoke smoke which is practically all of it may to a large extent be doce done away arifian Arifi Aa with in the opinion ot of N W shaw of L london adon with means already at our command for the abatement of the smoke nuisance mr shaw suggests precipitation chambers for each block of houses provided by the municipal ity in which the smoke may judy be treated before passing into the outer air mr shaw thinks that something like 7 tons of solid mattec matt c are thrown out by the chimneys of lon don every day the abatement of the dust can only be accomplished at present by the abatement of its causes chief among these Is the at britlon of pavements by the hoots hoofs of horses and the pulverizing of or i ganic mater by traffic much of this 4 could be avoided by the use of hard and smooth pavements frequently v ached and kept clean mr beaw 4 thinks that auto moiling should be en nsf cou raged in the cities as the ma chines make no dust to sensitize postal cards the popularity of illustrated postal cards makes it desirable to produce them at home by photography and all that Is needed tor for this Is the sensitize ing of the card to do this plunge the card into a 1 per cent solution of chloride of sodium common table salt and when it la Is dry brush the part it Is desired to sensitize with a brush which has been previously dipped in a 10 per cent solution ot of nitrate ot of silver still better results are had by adding to the 1 per cent salt solution an equal quantity of phosphate of soda after the printing the paper is washed only on the part that contains the image then it Is laid in the gold solution and finally fixed with then it must be washed and dried As these opera eions are all done with a brush they are accomplished rapidly doing them in a dim light of course gives the best resu ts is special scale for stores i quick service in a grocery store has come to be demanded and in fur therance of this demand it is custom ary to put up in advance packages of 0 the most needed commodities it Is for this work that a special scale has been designed the scale itself may be of any ordinary ordin ry pattern with the bual hopper or scoop and the tilting beam in addition thereto the in provides a source of electrical energy and a see secondary dary hopper mounted above the sea scale e hopper and capable of cutting off the feed the in slant stant the proper amount of the corn com kodity falls into the scoop suppose I 1 electrical meehan sm stops the flow the grocer desires to put up pound packages of coffee he ile places the counterpoise weight on the pound notch of the beam tilting the latter down and disconnecting the two con tact points which close the electrical circuit the coffee is placed in the hopper above the scoop and immedi abely begins to run into the scale when the proper quantity has fallen the beam tilts upward permitting the siring contact bar to rise and form the connection with mith the opposite lember member of the circuit closer this ansmits transmits the current directly to a magnet in the feeding hopper and closes oses a gate shutting off the supply instantly antly the false witness of the test bar mr buchanan in the engineering magazine propounds pro and answers the question wilether cast iron test bars truly indicate the strength of the cast ings they represent by altering the rate of cooling the strength ot of iron can be greatly changed and test bars are often run separately from the casting and cooled buic her ker so that they usually have greater strength sometimes more than twice as much separately cast test bars are always stronger than those cast on the cast leg ing itself and of the latter the one nearest the heaviest part of the cast ing Is always the weakest the rem edy as above indicated Is simple when the false witness has once been pointed out from field and laboratory prof A E wright of the army medical school at netley has pub fished the results obtained by anti typhoid inosculation fewer cases and fewest deaths occurred among those who ivere were inoculated than among those who were not W S simpson a british inventor has produced a rapid firing gun which can be operated with only 15 per cent ot of the recoil incident to ordinary ar practice it Is said to hayo have greater range and greater velocity than any other gun of its calibre A company has been formed to earlif ture at ampere X J pulp for paper out of wiste straw by a patent ed electrical process tho the pulp will ifil tor for 0 a ton and the inventor fiyo the 0 of electricity bleaches it 0 a 11 u a e of whiteness |
