462 Sykes c~iz,l d)~mmcJz/s. [J. F. I.,

AI)DENDUM.

While wri t ing these notes, a n o t h e r plan of measu re lnen t has occur red to me which would be useful as a check on

results ob ta ined bv the electrical m e t hod , a l t hough it has not the a d v a n t a g e of the la t ter in a l lowing results to be ob ta ined

unde r the same condi t ions as usual ly ob ta in 4n mach ine bear - il~gs. Th is xxould 1)e to have a long conical 1)earing, Fig. 3, accura te ly fitted to a solid b o x B, whose longi tud ina l pos i t ion with respect to the revoh, ing shaft .4 can be accura te ly loca ted

by means of a m ic roscope C, m o u n t e d on the b o x and focussed on a fine c i rcumferent ia l line on the shaft. T h e th ickness of the oil film in this case is d e t e r m i n e d hy the longi tudina l mot ion of B on .~. Differin K pressures be t w een shaft and b o x m a y be 1)roduced 1)y a spr ing or we igh t ed lever ac t ing on the

end of the l~ox at P. N'l'iR K K';' ( ) / IS KRV VFO RV, .~l AR('IT, 1897.

E To be concluded.]

N O T E S AND C O M M E N T S . ~

PROPOSED SHIP CANAL FROM T H E BALTIC TO THE BLACK SEA.

The Russiau governnlent is said to be seriously contemplat ing the con- struetion of a great ship canal between the Baltic and Black Seas, entirely through Russian territory, to connect the northern and southern portions of the empire. The military value of such a canal in permit t ing of a concentra- tion of all the available naval force of the empire at one or the other of these poiuts would unquestionably prove of the highest importance ; but, in addition to this obvious advantage, it is believed that its value to the agricultural and indnstrial iuterests of Russia would be scarcely less importaut.

We reprodnce from tile New York Sun the following data bearing on the subject :

After a thorough study of the\-ar ious possible roads, one has been selected as tile nlost practical, running, as it does, entirely through Russian territory. Oi1 the plan selected there are no great difficulties of level to be overeonle, al though the European watershed summit has to be crossed, but this last takes place at one of its lowest points.

The proposed canal 's entrance will be on the Gulf of Riga, at the mouth of the River Duna. It will follow the course of this river up to a point above Duv a- bourg. Then, leaving this valley, it reaches the Bereziua River by a straight cut and passes through Babronisk. This brings it into the Dnieper, and fo1-

*Froth t i le S e c r e t a r y ' s m o n t h l y repor t s .

Dec. . ~897. l X<~/c.~ atz<t C b m m e s z / s . 4 6 3

lowing t h i s na tu r a l dec l iv i ty it r e aches t h e Black Sea, o p e u i n ~ into a m;~,~: n i f icen t roads tead be low the Ker sou . T he to ta l l e n g t h of th i s colossal xw~ er- w a y wil l be s o m e t h i u g l ike L6oo k i l o m e t e r s (about Looo mi les ) , and it will ,b~: e x c a v a t e d to a d e p t h of 8 ~ m e t e r s (about 2 7 feet) . T h i s will a l low t h e larg- est i ron-c lads to nav iga t e it f ree ly f rom one emt to t h e o ther . T h e es t imal , 'd cost is p u t d o w n at $5oo,ooo,ooo.

I t s s t r a t eg ic i m p o r t a n c e does not need d e m o n s t r a t i o n . By t h e select ion ,~i a course r u n n i n g at a safe d i s t ance f rom t h e f ron t ie r , i t p laces back of ~he R u s s i a n forces s t a t i oned in P o l a n d an unas sa i l ab l e base of opera t ion . Fu l l y p ro t ec t ed a l r eady by a who le n e t w o r k of for t i f ica t ions and ra i lways , t h i s cana l is i n t e n d e d to act as a feeder for all t h e war mate r i a l . As to t h e concen t r a t i on of t h e w h o l e R u s s i a n fleet in t he Black Sea, t h i s m e a n s an abso lu te cont ro l ~)f C o n s t a n t i n o p l e a n d t he Strai ts .

But if t h i s en t e rp r i s e is of t h e u t m o s t i m p o r t a n c e in a m i l i t a r y po in t of view, i t wil l also p rove u n q u e s t i o n a b l y ve ry benef ic ia l to t h e ag r i cu l tu ra l alld i ndus t r i a l i n t e r e s t s of t h e coun t ry . I t p laces vas t g r a i n - p r o d u c i n g r eg ions in c h e a p c o m m u n i c a t i o n w i t h Odessa, t h e ch ie f po i n t of expor t , whi le the i m m e n s e coal f ields of S o u t h e r n R u s s i a will come in to eas ier connec t i on with t h e i ndus t r i a l d i s t r i c t s of Poland . T h e r e a re reasons , too, to bel ieve t ha t new fac tor ies will deve lop along" t h e cana l on a c c o u n t of t h e c h e a p n e s s of th i s new m o d e of t r anspor t . If t h i s s c h e m e h a s been adopted , t he r e is no doubt tha t t h e R u s s i a n t enac i t y will b r i n g it to success .

T E L F G R A P t t V W I T H O U T W I R E S .

T h e fo l lowing i n t e l l i g e n t s u m m a r y of t h e p r e s e n t s t a t u s of t h e p rob l em of t e l e g r a p h y is c o n d e n s e d f rom a r ecen t edi tor ia l u t t e r a n c e of t h e S'cie*zti/ic .4,zerican, a n d will be f ound of in t e res t :

N iko l a Tes la ha s la te ly a n u o u n c e d t h a t he ha s c o m p l e t e d h is wire less tek.- g r a p h to s u c h an e x t e n t as to p e r m i t of t e l e g r a p h y t h r o u g h t he ea r t h for a dis- t a n c e of t w e n t y mi l e s or nmre , a n d h is e x p e r i m e n t s sa t i s fy h i m of t he feasibi l i ty of wi re less t e l e g r a p h y on a m u c h m o r e e x t e n d e d scale. I n fact, h e a ims at n o t h i n g less t h a n t he e s t a b l i s h m e n t of a s y s t e m of t e l e g r a p h y t ha t sha l l i nc lude t he who le ear th , and by w h i c h i t e m s of n e w s m a y be d i s t r ibu ted f rom one pol i t ica l or c o m m e r c i a l c e n t e r to every o t h e r s u c h cen t e r t h r o u g h o u t t h e world . This , Mr. Tes la c la ims , is poss ib le w i t h o u t t h e i n t e r f e r ence of one set of s igua l s w i th ano the r .

H e h a s cons t ruc t e d and t e s ted b o t h t r a n s m i t t i n g and r ece iv ing appara tus . a n d h a s f o u n d t ha t a s u r p r i s i n g l y s m a l l e x p e n d i t u r e of e u e r g y is requi red . I t is imposs ib le , at t h i s wr i t ing , to secure de ta i l s of t h e appa ra tus , bu t it is k n o w n tha t he ut i l izes t he s ta t ic e q u i l i b r i u m of t he ear th . T h i s he d i s tu rbs at one point , m a k i n g s igna l s w h i c h can be d i s t i n g n i s h e d a t one or m o r e dis- t a n t po in ts .

In h i s ear l ier e x p e r i m e n t s in h i g h f r e q u e n c y c u r r e n t s Sir. Tes la a t ta ined a f r e q u e n e y of io,ooo pe r second ; now 2,eoo,ooo ose i l la t ions pe r second is not d e e m e d ex t rao rd i lmry . It is said t h a t t h e success of t h e sys ten i is assured, bu t he wil l no t come before t h e pub l i c un t i l eve ry deta i l is comple ted . It is u n d e r s t o o d t h a t t he t r a n s m i s s i o n of power f rom place to p lace by m e a n s of a s imi la r s y s t e m is c o n t e m p l a t e d .