44 



NATURE 



[March 20, 1919 



Graphical Methods in Nautical Astronomy. 



As the author of the article in Nature of October 24, 

 19 18, in which the diagram referred to by Dr. 

 Hutchinson last week was first brought to the 

 notice of your readers, may 1 be permitted to supple- 

 ment the information as to previous efforts in the 

 same direction? When the diagram first appeared 

 in this country Rear-Admiral Parry, Hydrographer to 

 the Admiralty, also set on foot an inquiry similar to 

 that of Dr, Hutchinson, and very courteously sent 

 me the result of his investigation. From his report it 

 appears that "an account of the ' Nomogramme ' was 

 published in Petermann's Mittelungen (vol, ii., pp. 182 

 and 249, 1913), and was illustrated by a skeleton 

 diagram similar in principle to these charts, and the 

 method for using it was fully explained." This, in 

 point of time, is fifteen years later than the date of 

 the paper of M. d'Ocagne, who, so far as appears at 

 present, is clearly entitled to the credit claimed for 

 him as first in the field. 



The share of Mr. Littlehales, however, is marked 

 by two features of interest : — (i) That he seems to 

 have been the first to prepare and publish the dia- 

 gram in a form that promises to be useful in the 

 navigation of air and ocean, and {2) that the sim- 

 plicity of treatment which deduces the principle and 

 graduation of the chart directly from a general for- 

 mula of spherical trigonometry renders the theory of 

 the matter intelligible to many nautical persons to 

 whom the mysteries of " Nomographic " are as a 

 sealed book. H. B. Goodwin. 



March 15. 



The Oldest Mosquitoes. 



The Rev. Peter Bellinger Brodie, in his " His- 

 tory of the Fossil Insects of the Secondary Rocks of 

 England," gave a figure of a small fly which he 

 named Ctilex (?) fossilis. This insect, from the 

 Purbeck strata, would be by far the oldest mosquito 

 known, were it a veritable Culex. Unfortunately, it 

 is impossible to form any definite opinion, and as 

 positive evidence of the antiquity of the Culicidae the 

 specimen must be dismissed as valueless. On general 

 grounds it is very improbable that the group is so 

 ancient. In Handlirsch's great work on fossil insects 

 several Culicidae are listed from the Oligocene Ter- 

 tiary; but Handlirsch did not know that two species 

 described by Scudder, from Wyoming and Utah 

 respectively, are actually inuch older, coming from 

 Eocene rocks. The one from Utah is of little value, 

 and presumably not a true Culex; but that from the 

 Green River beds of W3'oming has the unmistakable 

 features of a genuine mosquito, showing the long 

 proboscis and the short palpi of the female. Accord- 

 ing to Schuchert's estimates of geologic time, this 

 should be more than two million years old at the 

 very least. Scudder 's insect, called Ctilex damna- 

 torurth, is 6 mm. long, with a proboscis 19 mm. It 

 doubtless tormented the Eohippus and related 

 mammals of this general period. Whether it carried 

 any pathogenic protozoa we can, of course, never 

 know. It is now possible to put on record a second 

 Eocene mosquito, found by Mr. Dean E. Winchester, 

 of the U.S. Geological Survey, at Smith's Ranch, in 

 the vicinity of the Cathedral Bluffs, in western 

 Colorado. It is represented by a female, preserved in 

 lateral view, 52 mm. long, the wing about 4-2 mm., 

 fhorax about 2 mm., palpi about 04 mm., and the 

 distinctly curved proboscis 3 mm. The stout 

 abdomen is like that of true Culex, obtuse at the 

 end, not tapering as in Aedes. The longer proboscis 

 readily separates it from Scudder 's insect, so it must 

 stand as a new species, to be called Culex winchesteri, 



NO. 2577, VOL. 103] 



' after its discoverer. The horizon is considered to be 

 Green River, approximately equivalent to that of the 

 Wyoming locality. 



The oldest British mosquitoes, setting aside Brodie 's 

 very dubious Purbeck specimen, are three species from 

 the Oligocene of Gurnard Bay, in the Isle of Wight, 

 also collected by Brodie. These were described by the 

 present writer in 1915, and are in the U.S. National 

 Museum. One of them is so beautifully preserved 

 that it shows the wing-scales. 



While writing on fossil Diptera I take occasion to 

 note that my Mesomyites concinnus, another of the 

 'Gurnet Bay fossils, is evidently a member of the 

 peculiar Tipulid genus Styringomyia, and should be 

 called Styringomyia concinna. I am indebted to Mr. 

 C. P. Alexander for suggesting the correction. The 

 specimen is in the British Museum. 



The Gurnard Bay locality, which furnished Brodie 

 with large and important collections, seems not to 

 have been investigated in recent years. Most of 

 Brodie's collection is at the British Museum, and will, 

 when fully described, add greatly to our knowledge of 

 Tertiary insects. T. D. A. Cockerell. 



University of Colorado, Boulder, Colorado. 



Proposed Magnetic and Allied Observations during the 

 Total Solar Eclipse of May 29, 1919. 



Special magnetic and allied observations will be 

 made at certain stations inside and outside the 

 shadow belt of the total solar eclipse of May 29 next 

 by the Department of Terrestrial Magnetism of the 

 Carnegie Institution of Washington and by various 

 magnetic observatories, institutions, and individuals. 

 The probable stations of the Department of Terres- 

 trial Magnetism are (i) La Paz, Bolivia; (2) Huan- 

 cayo (north of belt of totality) ; (3) near Sobral, 

 Brazil; (4) He Principe or Libreville, French Congo; 

 and (5) various field stations within the zone of visi- 

 bility. At station (3) complete magnetic and electric 

 observations will be made. 



The general scheme of work proposed by the Depart- 

 ment of Terrestrial Magnetism is as follows : — 



(i) Simultaneous magnetic observations of any or all 

 of the elements, according to the instruments at the 

 observer's disposal, every minute from May 29 next, 

 9h. 58m. a.m. to 4h. 321T1. p.m. Greenwich civil mean 

 time, or from May 28, 2ih. 58m. to 4h. 32m. May 29, 

 Greenwich astronomical mean time. 



(To ensure the highest degree of accuracy, the 

 observer should begin to work early enough to have 

 everything in complete readiness in proper time. Past 

 experience has shown it to be essential that the same 

 observer should make the readings throughout the 

 entire interval. If possible, similar observations for 

 the same interval of time as on May 29 should be 

 made on Mav 28 and 30, to afford some means of 

 determining the undisturbed course of the magnetic 

 declination.) 



(2) At magnetic observatories all necessary pre- 

 cautions should be taken to ensure that the self- 

 recording instruments will be in good operation, not 

 only during the proposed interval, but also for some 

 time before and after, and eye-readings should be 

 taken in addition wherever it is possible and con- 

 venient. 



(It is recommended that, in general, the magneto- 

 graph should be run on the usual speed throughout the 

 interval, and that, if a change in recording speed be 

 made, every precaution possible should be taken to 

 j?uard against instrumental changes likely to affect 

 the continuity of the base line.) 



(3) Atmospheric-electric observations should be 

 made to the extent possible with the observer's equip- 



