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Hydrodynamic imitation of electric phenomena
312
Trepanning Oysters.
[Jour. Fremk. Inst.,
v e r y i m p o r t a n t w o r k , w h i c h will s u r p a s s in e x t e n t e v e r y t h i n g of t h e k i n d that has hitherto been undertaken. In Belgium measurements have been for 8,477 d i f f e r e n t localities. T h e l e v e l i n g , w h i c h is n o w i n progress i n H o l l a n d , t h o u g h Ok a n a r r o w e r scale, is r e m a r k a b l e for its precision. I n G e r m a n y o p e r a t i o n s b e g a n i n 1865 ~ n d will p r o b a b l y be c o m p l e t e d i n 1887. I n R u s s i a t h e w o r k h a s b e e n i n p r o g r e s s s i n c e 1873. A n i n t e r e s t i n g p o i n t , w h i c h w i l l soon b e d e t e r m i n e d , is t h e difference of level b e t w e e n t h e B a l t i c a n d t h e B l a c k seas. T h e S p a n i s h o p e r a t i o n s h a v e s h o w n t h a t t h e level of t h e A t l a n t i c a t S a n t a n d e r is 0~582 m e t r e s a b o v e t h a t of t h e M e d i t e r r a n e a n a t Alicant.--Ann. des Ponts et Chauss., M a r c h , 1884. C. IIV[PO]4TATION OF ~3~IEI%ICAN (~RAPES INTO FI%ANCE.---Ch. J o l y h a s preSented a p a p e r to t h e £'ocigt~ d'I[orticulture, u p o n t h e i m p o r t a t i o n of m u s cat g r a p e s from t h e U n i t e d S t a t e s i n t o F r a n c e . T h e g r a p e s were p r e s e r v e d in a n a q u e o u s s o l u t i o n of glucose. T h e a t t e n t i o n of t h e g r a p e g r o w e r s of F r a n c e a n d A l g i e r s is i n v i t e d to t h e i m p o r t a n t c o n s e q u e n c e s w h i c h m a y follow t h i s i m p o r t a t i o n . T h e U n i t e d States, o u t s i d e of t h e i r e n o r m o u s g r a i n t r a d e , h a v e h i t h e r t o b e e n l i m i t e d to t h e e x p o r t of fruits p r e p a r e d b y a p r e v i o u s d r y i n g , w h i c h r e m o v e s a b o u t 85 p e r c e n t . of t h e w a t e r t h a t t h e y c o n t a i n ; t h i s opera'tion h a s t h e d o u b l e a d v a n t a g e of d i m i u i s h i n g t h e .............. ~ ] a n d of f a c i l i t a t i n g t h e p r e s e r v a t i o n of t h e fruit. ±vL J o l y , w i n l e c a l l i n g a t t e n t i o n to t h e d a n g e r of a n i n t e r f e r e n c e w i t h t h e F r e n c h g r a p e trade, u r g e s c u l t i v a t o r s to i n c r e a s e t h e i r p r o d u c t i o n as m u c h as possible, chiefly b y t h e r a t i o n a l a m e l i o r a t i o n o f t h e i r m e t h o d s of culture.--23a. Nature, M a y 3, 1884. C. I-IYDRODYNAI'¢IIC ]_MITATION OF ELECTRIC PHENOMENA.--1)eeharme, h a v i n g i m i t a t e d , by l i q u i d or gaseous c u r r e n t s , t h e p r i n c i p a l p h e n o n m n a of s t a t i c a n d d y n a m i c electricity, e l e c t r o m a g n e t i s m , e l e e t r o d y n a m i c s , induction, electrochemistry, and even e]ectrophysiology, concludes that electric a n d m a g n e t i c p h e n o m e n a are s i m i l a r to h y d r o d y n a m i c p h e n o m e n a ; i n ~ o t h e r w o r d s t h a t electricity, u n d e r t h e f o r m of a n m t b e r e a l or p o n d e r a b l e c u r r e n t , is a n a l o g o u s to a l i q u i d c u r r e n t , a n d , w h e n in a s t a t e of t e n s i o n , r e s e m b l e s a q u a n t i t y of l i q u i d d i f f u s i n g i n a jet. E l e c t r i c m o v e m e n t is t h e n a t r u e flow a n d n o t a m e r e v i b r a t i o n . I t s e q u i p o t e n t i a l l i n e s m a y be e x a c t l y r e p r e s e n t e d b y L a m ~ s d i f f e r e n t i a l e q u a t i o n for t h e c u r v e s of h y d r a u l i c level. T h e r e a r e some electric p h e n o m e n a , h o w e v e r , w h i c h a p p e a r to be t h e .result of v i b r a t o r y a n d g y r a t o r y m o v e m e n t s ; b u t t h e s e m o v e m e n t s n a t u r a l l y r e s u l t f r o m tl~e t r a n s f o r m a t i o n of w a v e m o t i o n i n a c o n t i n u o u s current.--Ann, de Chirn. ct de JPhys., A p r i l , 1884. C.
TREPA~NI]~'(~ 0YSTElCS.--Bauchon B r a n d e l y , i n o r d e r to s t u d y t h e e m b r y o n i c g r o w t h of t h e oyster, p e r f o r a t e d t h e u p p e r s h e l l s b y m e a n s of a trep a n . A f t e r t h e hole is m a d e a n d t h e particles of t h e s h e l l c a r e f u l l y r e m o v e d t~ s t o p p e r is p r e p a r e d of l i n e n , w a x or some o t h e r m a t e r i a l , to e x c l u d e t h e w a t e r a n d t h e e n e m i e s of t h e oyster. T h e s h e l l is r e c o n s t r u c t e d b y a t h i n l a y e r of p e a r l i n a b o u t e i g h t days. I n o r d e r to p r e v e n t t h e g r o w t h b e i n g too r a p i d w h i l e t h e o b s e r v a t i o n s are g o i n g on, t h e s t o p p e r is t u r n e d a r o u n d e v e r y t w o or t h r e e days.--aSes Mondes, A p r i l 19, 1884. C.
Trepanning Oysters.
[Jour. Fremk. Inst.,
v e r y i m p o r t a n t w o r k , w h i c h will s u r p a s s in e x t e n t e v e r y t h i n g of t h e k i n d that has hitherto been undertaken. In Belgium measurements have been for 8,477 d i f f e r e n t localities. T h e l e v e l i n g , w h i c h is n o w i n progress i n H o l l a n d , t h o u g h Ok a n a r r o w e r scale, is r e m a r k a b l e for its precision. I n G e r m a n y o p e r a t i o n s b e g a n i n 1865 ~ n d will p r o b a b l y be c o m p l e t e d i n 1887. I n R u s s i a t h e w o r k h a s b e e n i n p r o g r e s s s i n c e 1873. A n i n t e r e s t i n g p o i n t , w h i c h w i l l soon b e d e t e r m i n e d , is t h e difference of level b e t w e e n t h e B a l t i c a n d t h e B l a c k seas. T h e S p a n i s h o p e r a t i o n s h a v e s h o w n t h a t t h e level of t h e A t l a n t i c a t S a n t a n d e r is 0~582 m e t r e s a b o v e t h a t of t h e M e d i t e r r a n e a n a t Alicant.--Ann. des Ponts et Chauss., M a r c h , 1884. C. IIV[PO]4TATION OF ~3~IEI%ICAN (~RAPES INTO FI%ANCE.---Ch. J o l y h a s preSented a p a p e r to t h e £'ocigt~ d'I[orticulture, u p o n t h e i m p o r t a t i o n of m u s cat g r a p e s from t h e U n i t e d S t a t e s i n t o F r a n c e . T h e g r a p e s were p r e s e r v e d in a n a q u e o u s s o l u t i o n of glucose. T h e a t t e n t i o n of t h e g r a p e g r o w e r s of F r a n c e a n d A l g i e r s is i n v i t e d to t h e i m p o r t a n t c o n s e q u e n c e s w h i c h m a y follow t h i s i m p o r t a t i o n . T h e U n i t e d States, o u t s i d e of t h e i r e n o r m o u s g r a i n t r a d e , h a v e h i t h e r t o b e e n l i m i t e d to t h e e x p o r t of fruits p r e p a r e d b y a p r e v i o u s d r y i n g , w h i c h r e m o v e s a b o u t 85 p e r c e n t . of t h e w a t e r t h a t t h e y c o n t a i n ; t h i s opera'tion h a s t h e d o u b l e a d v a n t a g e of d i m i u i s h i n g t h e .............. ~ ] a n d of f a c i l i t a t i n g t h e p r e s e r v a t i o n of t h e fruit. ±vL J o l y , w i n l e c a l l i n g a t t e n t i o n to t h e d a n g e r of a n i n t e r f e r e n c e w i t h t h e F r e n c h g r a p e trade, u r g e s c u l t i v a t o r s to i n c r e a s e t h e i r p r o d u c t i o n as m u c h as possible, chiefly b y t h e r a t i o n a l a m e l i o r a t i o n o f t h e i r m e t h o d s of culture.--23a. Nature, M a y 3, 1884. C. I-IYDRODYNAI'¢IIC ]_MITATION OF ELECTRIC PHENOMENA.--1)eeharme, h a v i n g i m i t a t e d , by l i q u i d or gaseous c u r r e n t s , t h e p r i n c i p a l p h e n o n m n a of s t a t i c a n d d y n a m i c electricity, e l e c t r o m a g n e t i s m , e l e e t r o d y n a m i c s , induction, electrochemistry, and even e]ectrophysiology, concludes that electric a n d m a g n e t i c p h e n o m e n a are s i m i l a r to h y d r o d y n a m i c p h e n o m e n a ; i n ~ o t h e r w o r d s t h a t electricity, u n d e r t h e f o r m of a n m t b e r e a l or p o n d e r a b l e c u r r e n t , is a n a l o g o u s to a l i q u i d c u r r e n t , a n d , w h e n in a s t a t e of t e n s i o n , r e s e m b l e s a q u a n t i t y of l i q u i d d i f f u s i n g i n a jet. E l e c t r i c m o v e m e n t is t h e n a t r u e flow a n d n o t a m e r e v i b r a t i o n . I t s e q u i p o t e n t i a l l i n e s m a y be e x a c t l y r e p r e s e n t e d b y L a m ~ s d i f f e r e n t i a l e q u a t i o n for t h e c u r v e s of h y d r a u l i c level. T h e r e a r e some electric p h e n o m e n a , h o w e v e r , w h i c h a p p e a r to be t h e .result of v i b r a t o r y a n d g y r a t o r y m o v e m e n t s ; b u t t h e s e m o v e m e n t s n a t u r a l l y r e s u l t f r o m tl~e t r a n s f o r m a t i o n of w a v e m o t i o n i n a c o n t i n u o u s current.--Ann, de Chirn. ct de JPhys., A p r i l , 1884. C.
TREPA~NI]~'(~ 0YSTElCS.--Bauchon B r a n d e l y , i n o r d e r to s t u d y t h e e m b r y o n i c g r o w t h of t h e oyster, p e r f o r a t e d t h e u p p e r s h e l l s b y m e a n s of a trep a n . A f t e r t h e hole is m a d e a n d t h e particles of t h e s h e l l c a r e f u l l y r e m o v e d t~ s t o p p e r is p r e p a r e d of l i n e n , w a x or some o t h e r m a t e r i a l , to e x c l u d e t h e w a t e r a n d t h e e n e m i e s of t h e oyster. T h e s h e l l is r e c o n s t r u c t e d b y a t h i n l a y e r of p e a r l i n a b o u t e i g h t days. I n o r d e r to p r e v e n t t h e g r o w t h b e i n g too r a p i d w h i l e t h e o b s e r v a t i o n s are g o i n g on, t h e s t o p p e r is t u r n e d a r o u n d e v e r y t w o or t h r e e days.--aSes Mondes, A p r i l 19, 1884. C.