256 



SCIENCE. 



to go on training your students to the new terms — some 

 of which you or others will doubtless see reasons for 

 changing — to improve as far as possible, fill up blanks, 

 perhaps get up a small manual in which the new' terms 

 shall be practically applied, and have faith that sooner 

 or later the best part of your innovations will find their 

 way into scientific use. The plan is an excellent one, 

 it is a new garment which will fit Science well, if that 

 capricious and fantastic and old-fashioned dressing lady 

 can only be induced to try it on. 



Always very truly yours, 



O. W. Holmes. 



A CURIOUS EGG. 

 E. E. Barnard. 



One of my hens of the " Dominico " breed is account- 

 able for the presence to-day of a most remarkable egg, 

 which was found in the hen's nest. This singular object 

 measured about three inches in its longest diameter, a 

 round oval in shape, not like the ordinary egg with a 

 large and a small end. The shell was thin and soft to 

 the touch, resembling the " skin " that is found inside an 

 eggshell. Pressing on one end of the egg, a hard object was 

 felt inside the shell. Opening the egg, by cutting with a 

 sharp knife, two eggs were found, one perfect with a hard 

 shell, slightly smaller than the ordinary egg, the other 

 perfect in every respect, save that it possessed no shell. 

 The egg with the shell was enclosed in the white of the 

 other. These two eggs occupied the two ends of the 

 original shell. Upon opening the one with the hard 

 shell it was found to be perfect. Putting the two eggs in 

 separate cups, the one which had the hard shell was 

 slightly smaller and its yolk of a pale yellow ; the yolk of 

 the other was somewhat deeper in color. 



Here we have a rare phenomenon ; first a large egg 

 with slightly soft shell ; inside this two eggs, one perfect 

 in a hard shell, the other without shell but otherwise 

 perfect. 



Nashville, Tenn., May 9. 



BOOKS RECEIVED. 



A Memorial of Joseph Henry. Published by order 

 of Congress, Washington, 1880. 



The present volume presents in a handsome and conve- 

 nient form the historical facts relating to the career of 

 Professor Joseph Henry, and a record of the various 

 ceremonies and memorial exercises celebrated after his 

 death in honor to his memory. 



The memorial exercises at the Capital include ad- 

 dresses by President Garfield, Hannibal Hamlin, Robert 

 E. Withers, Professor Asa Gray, William B. Rogers, 

 General Sherman and others. 



The concluding words of President Garfield's address 

 may well be quoted as conveying the general esteem in 

 which Professor Henry was held by all who knew him. 

 " Remembering his great career as a man of science, as 

 a man who served his Government with singular ability 

 and faithfulness, who was loved and venerated by every 

 circle, who blessed with the light of friendship the 

 worthiest and the best, whose life added new lustre to the 

 glory of the human race, we shall be most fortunate, if 

 ever in the future, we see his like again." 



NOTES. 



Recent experiments by M. Grehaut, prove that the quan- 

 tity of carbonic acid exhaled by any one individual of an 

 animal species is about constant. Fifty litres of air passed 

 through the lungs of a dog, 9kg. weight, yielded 2.747 gr. of 

 CO a . Eight days after the experiment was repeated, and 



the C0 2 was 2.810 gr. In man, the same volume of air cir- 

 culating through the lungs, receives 3.333 gr. of CO a . Irri- 

 tations and inflammations of the respiratory mucous mem- 

 brane (e. g. through inhaling sulphurous acid), considera- 

 bly decrease the exhalation of C0 2 . The gas then tends 

 to accumulate in the blood. 



Galvanic Gilding. — M. Rod gives the composition of a 

 bath to be used at temperatures from 50 to 8o° C. It con- 

 sists of 60 parts crystalline phosphate of soda, 10 parts 

 bisulphate of soda, 1 part cyanide of sodium, 2% parts 

 chloride of gold, and 1,000 distilled water. In order to 

 prepare the bath the water is divided into three portions of 

 700, 150, and 150 respectively. The phosphate of soda is 

 dissolved in the first lot, the chloride of gold in the second, 

 and the other ingredients in the third. The two first por- 

 tions are gradually mixed together, and the third is then 

 slowly added. A platinum plate is used as anode. — Le 

 Monde de la Science. 



Radiation through Ebonite. — Captain Abney exhib- 

 ited at the Physical Society of London, a number of photo- 

 graphic negatives taken by himself and Colonel Festin by 

 radiation through thin sheets of ebonite. The light from 

 the positive pole of an electric lamp was sent through a 

 thin sheet of ebonite -/fin. thick, and photographs taken 

 showed the radiation to have a low wave-length, from 8,000 

 to 14,000. The carbon points of the lamp could be photo- 

 graphed through the sheet, and Colonel Festin observed 

 the sun's disc through it. The ebonite showed a grained 

 structure, and different samples of ebonite gave different 

 results, but all gave some result, in course of time at least; 

 old ebonite, like that used in some of Mr. Preece's experi- 

 ments, scattering the light more than new ebonite. Dr. 

 Moser exhibited the passage of the rays through the ebonite 

 to the audience by means of a galvanometer. Professor 

 Guthrie observed that Captain Abney had proved that 

 light as well as heat traversed the ebonite, and Dr. Coffin 

 stated that compositions of ebonite, apparently the same, 

 might vary considerably. 



Photographic Photometry. — A promising application 

 of photography to precise measurement of phenomena of 

 light has been recently tried by M. Janssen. The method 

 is advantageous in that photography reveals the action of 

 the extremely weak luminous and the ultra-violet rays ; but 

 the chief advantage lies in the permanence of the results 

 as against the fugitive nature of ordinary photometric com- 

 parisons, which, too, require the simultaneous presence of 

 the two light sources. The various amounts of metallic 

 deposit on the photographic plate cannot well be weighed, 

 so M. Janssen measures by the degree of opacity produced. 

 His photometer consists of a frame with sensitised plate, 

 before which is passed at a known rate of uniform motion 

 a shutter having a slit. If this slit were rectangular, a 

 uniform shade would be produced on the plate; but by 

 making it triangular he obtains a variation of shade, de- 

 creasing from the side corresponding to the base of the tri- 

 angle to that corresponding to the apex. It is further 

 proved that the photographic deposit does not increase as 

 rapidly as the luminous intensity. Now, to compare the 

 sensibility of two plates differently prepared, they have 

 merely to be exposed successively in the frame under like 

 conditions, and the points where they show the same opacity 

 being compared to the points of the triangular slit corre- 

 sponding to them, the ratio of the apertures at those points 

 expresses the ratio of sensibility. Thus the new gelatino- 

 bromide of silver plates are proved to be twenty times as 

 sensitive as the collodion plates prepared by the wet pro- 

 cess. Again, to compare two luminous sources, they are 

 made to act successively on two similar plates in the pho- 

 tometer, and the points of equal shade in the plates indi- 

 cate, as before, the relation sought. M. Janssen has com- 

 pared the light of the sun and some stars on these principles, 

 preparing from the former "solar scales" (with uniform 

 degradation of shade), under exactly determined conditions 

 as to sensitive layer, time of solar action, height of the sun, 

 etc. Circular images of stars are obtained by placing a 

 photographic plate a little out of focus in the telescope, 

 and a series of these, got with different times of exposure, 

 are compared with the scales obtained from sunlight. M. 

 Janssen will shortly make known some of his results. 



