292 



SCIENCE. 



is the ingenious arrangement whereby, by simply turning 

 the caps with the diaphragms, orthoscopies or pseudos- 

 copic effect can be produced instantly at pleasure. It is 

 more particularly available for tubes of short 'length for 

 which the Wenham prism is inapplicable. 



Powell and Leland have completed a new 1-12 having 

 two front lenses. The maximum numeiical aperture is 

 1.43 (= 140 in crown glass of mean index 1.525), ob- 

 tained by a front lens several degrees greater than a 

 hemisphere, mounted on a plate of glass .003 inch in 

 thickness, which is itself mounted in the usual metal 

 woik by the zone projecting beyond the circumference of 

 the lens. With this front lens the focal distance from 

 the exposed surface of the plate on which the lens is 

 mounted is .007 inches. A second front, nearly a hemi- 

 sphere, is mounted in the usual way by a burred edge of 

 metal covering the extreme margin of the lens. This 

 front gives a numerical aperture of 1.28 (= 115 in glass) 

 and the focal distance is then 0.16 inch. The third front 

 provides a numerical aperture of 1.0 (=82° in glass, as 

 nearly as possible), and the working distance is then .024 

 inch — probably the greatest working distance hitherto 

 obtained with a 1-12 of that aperture. 



Dr. Reidel, an assistant to Professor Abbe, has found 

 two new fluids suitable for homogeneous objectives. The 

 first is a solution of Gum Damar dissolved in hot oil of 

 cedar-wood. The oil which is obtained in Germany has 

 a refractive index of 1.51 only, but by the Damar this 

 can be raised to 1.54. If carefully distilled it becomes 

 sufficiently pale and loses its stickiness. The other 

 medium is a solution of iodafe of zinc in Price's ordinary 

 glycerine in — 1.46). This salt is very soluble in glycer- 

 ine, and a refractive index of 1.56 or more can be ob- 

 tained, and therefore there is no difficulty in making a 

 solution of 1.52 which is the standard index at 18 cent. 

 Professor Abbe has furnished Mr. Zeiss with a new form- 

 ula for homogeneous \ , this having a numerical aperture 

 of 1.40 and adjusted for the new fluids. 



Mr. T. Charters White, R. M. S., calls for some re-agent 

 suitable for mounting insects ; carbolic acid renders the 

 chitinous envelope transparent, but has the same effect on 

 the internal organs also. Dr. Mathews also objected to 

 carbolic acid, as it caused the abdomen of insects thus 

 mounted to collapse. Those who have had some experi- 

 ence in making preparations for insect anatomy will per- 

 haps have suggestions to make. 



We lately called attention to infusoria found in 

 cases of epidemic catarrh, called Asthematos ciliaris. 

 Dr. Leidy doubted the character of this form and sug- 

 gested its being a ciliated epithelium. Dr. Carter now 

 maintains that it is correct to call it an infusorium, be- 

 cause by culture in mucus outside the body, they increase 

 in number, and they are found in morbid secretions of the 

 conjunctiva where no ciliated epithelia exist — more- 

 over, those remedies only cure the disease which kill the 

 Asthematos. 



THE STEREORACHYS. 



A new specimen of this gigantic and marvellous reptile 

 from the permian schists of Igornay (Saone and Loire) has 

 been presented by M. Gaudr3% who gives an exceedingly 

 interesting description of it. Among the results formulated 

 by the learned paleontologist, one of the most striking is 

 the continuity of life of the primary epoch to the secondary 

 one. We are tending more and more to the idea of the slow 

 modifications of terrestrial conditions, and are therefore re- 

 ceiving more and more from the gratuitous supposition of 

 the revolutions of the globe. 



To the Editor of "SCIENCE:" 



Dear Sir : — In the last number of your valuable 

 periodical, at the close of a review of Professor Packard's 

 work on the " Brain of the Locust," the writer states : 

 " In view of the loudly trumpeted theory recently re- 

 vived by Dr. J. J. Mason, after having repeatedly re- 

 ceived the coup de grdce at the hands of Stieda, Mey- 

 nert and others that large cells are motor, it is interesting 

 to note that those of the optic ganglion in the locust are 

 among the largest cells in its nervous system." 



This is a complete error, so far as I am concerned. 

 No such claim has ever been made by me in any form, 

 by hint, inference or otherwise. In my last paper on the 

 dimensions of nuclei there appears this sentence : " At 

 the same time it may be true that all large cells connect 

 with motor filaments. The sentence which immediately 

 precedes this one clearly proves that I refer here exclu- 

 sively to the spinal cord of turtles. This is reviving no 

 theory. Yours truly, 



John J. Mason. 



Newport, June 13, 1881. 



SUN SPOTS. 



The following record of observations, made by Mr. D. P. Todd, Assistant, has been forwarded by Prof. S. 

 Newcomb, U. S. Navy, Superintendent Nautical Almanac Office, Washington, D. C, to Gen. H. B. Hazen. 



DATE. 

 APRIL, 18: 



2, 9 a.m 



3, 10 a m 



5, 8 a.m 



6, 7 a.m 



7, 7 a.m 



10, 10 a.m 



11, 8 a.m 



14, 8 a.m 



15, 8am 

 17, 7 a.m 

 21, 9 a.m 



23, 7 a.m 



24, 9 a.m 

 26, 8am 

 28, 7 a.m 



8 a.m 

 30, 9 a.m 



Number of New 



Groups. Spots. 



5 

 11 



o 

 3 

 3 

 3 

 o 



15 



t20 

 IS 



t6o 

 o 



DlSAPPKARED BY 



Solar Rotation. 



Groups. Spots. 



|20 



10 

 10 

 t4S 



Reappeared by 

 Solar Rotation. 



Groups. Spots 



Total Number 

 Visible. 



Groups. Spots. 



10 



f20 



{20 

 tiS 



14 

 8 



7 



f20 



T4° 



tss 



t8 5 



t-60 

 tss 



10 

 10 

 5 



REMARKS. 



Few faculas. 



Faculas. 



Faculas. 



Faculae. 



Faculae. 



Faculae. 



Faculas. 



I Faculas. Many of the spots small. 



Faculas. Many of the spots small. 

 Faculae. Many of the spots small. 



Spots probably disappeared by 



solar rotation. 



I Faculas. Many of the spots small. 



^ Faculas. 

 Faculae. 



t Approximated. 



