58 



NATURE 



[November 21, 1895 



truly, that physically even less than one-tenth second is 

 sufficient to make the maximum impression on the eye, 

 and conclude that a longer duration is therefore un- 

 necessary. This would be a sound conclusion were the 

 atmosphere always clear, but it is not so. Now it is 

 physically true, as they admit, that the duration necessary 

 for the full effect of a flash depends on the intensity of 

 the light ; a weaker flash must have a longer duration 

 than a stronger one, to make the full effect on the retina. 

 But by the time a powerful flash has pierced a few miles 

 of hazy atmosphere, it is no longer powerful, and if it has 

 not a duration suitable to its reduced power, it will not 

 be seen so far. This is a question which cannot be 

 settled on merely theoretical grounds, but must inevit- 

 ably be a matter of experience. The following are a few 

 figures showing the great power of some modern light- 

 house apparatus now in use in the Trinity House and 

 Northern Lighthouse Services, as compared with anything 

 employed during the days of colza oil, fixed lights, and 

 apparatus of many sides. 



The Isle of May light has a calculated intensity of no 

 less than 26,000,000 candles to each flash, while the St. 

 Catherine's electric light, calculated on the same basis, 

 has a strength of beam equal to 5,000,000 candles. The 

 power of the La Heve electric light is stated at 23,000,000 

 candles. 



Turning now to the ordinary lights, where paraffin oil 

 is the illuminant, the following may be mentioned as 

 being of very great power. The Bishop Rock, biform, 

 with two eight-wick burners and hyper-radiant apparatus, 

 gives a flash of 175,000 candles. The Eddystone, with 

 two six-wick burners and first order apparatus, gives a 

 flash of 75,000 candles. Sule Skerry, with one six-wick 

 burner and hyper-radiant apparatus, gives a flash of 

 74,000 candles, and Fair Isle North, one six-wick burner 

 and hyper-radiant apparatus, without upper and lower 

 prisms, gives a flash of 72,000-candle power. 



The result of recent improvements in the optical 

 apparatus used in lighthouses, and in the increased power 

 of the lamps, is that the mariner is now getting the 

 benefit of lights of greater intensity and more charac- 

 teristic appearance, easily and rapidly recognisable. 



THE DEPARTMENT OF ENTOMOLOGY IN 



THE U.S. NATIONAL MUSEUM. 



'X'HE staff of the Department of Insects of the U.S. 



-*■ National Museum has been reorganised, as a result 



■of the death of the former Honorary Curator, Prof. C. V. 



Riley. 



The reorganisation has been effected by the appoint- 

 ment of Mr. L. O. Howard, Entomologist of the U.S. 

 Department of Agriculture, to the position of Honorary 

 Curator of the Department of Insects ; of Mr. Wm. H. 

 Ashmead to the position of Custodian of Hymenoptera ; 

 and Mr. D. W. Coquillett to the position of Custodian of 

 Diptera. All Museum custodians are honorary officers. 

 IVJr. M. L. Linell will remain as general assistant to the 

 Honorary Curator. 



The Department is at present in excellent working 

 ■condition. It contains a very great amount of material 

 in all orders, and in many unusual directions surpasses 

 any collection in the United States. Among others, the 

 following are of especial interest :— 



(i) The large collection, in all orders, of the late Prof. 

 C. V. Riley. 



(2) All of the material gathered during the past eighteen 

 years by correspondents, field agents, and the office staff 

 of the Division of Entomology, U.S. Department of 

 Agriculture. 



(3) The greater part of the collection of the late Asa 

 Fitch. 



(4) The large collection, in all orders, of the late G W. 

 Belfrage. 



NO. 1360, VOL. 53] 



(5) The collections in Lepidoptera and Coleoptera 

 made by Dr. John B. Smith down to 1889, together with 

 the types of the Noctuida; since described by Dr. Smith. 



(6) The collection of Lepidoptera of the late O. Meske. 



(7) The collection of Lepidoptera of G. Beyer. 



(8) The collection of Coleoptera of M. L. Linell. 



(9) The bulk of the collection, in all orders, of the late 

 H. K. Morrison. 



(10) The collection of Diptera of the late Edward 

 Burgess. 



(11) The type collection of Syrphidae made by Dr. 

 S. yN. V^illiston. 



(12) The collection of Ixodidas of the late Dr. George 

 Marx. 



(13) The collection of Myriopoda of the late C. H. 

 BoUman. 



(14) Sets of the Neo-tropical collections of Herbert 

 Smith. 



(15) The collection of Hymenoptera of V^m. J. Fox. 



(16) The collection of Tineina of Wm. BeutenmuUer. 



(17) The large Japanese collection, in all orders, of Dr. 

 K. Mitsukuri. 



(18) The African collections, in all orders, of Dr. 

 W. S. Abbott, Wm. Astor Chanler, J. F. Brady, the last 

 "Eclipse" expedition to West Africa, and of several 

 missionaries. 



(19) The large collection from South California of 

 D. W Coquillett, in Coleoptera, Hymenoptera, Lepi- 

 doptera and Orthoptera. 



(20) The Townend Glover manuscripts and plates. 



In addition to this material, there are minor collections 

 which have been the result of the work of Government 

 expeditions, or are gifts from United States Consuls and 

 many private individuals. 



This enormous mass of material is being cared for by 

 the active and honorary force of the Department, and the 

 perpetuity of the collection is assured. The National 

 Museum building is fireproof, and this, together with the 

 fact that it is a National institution, renders the Depart- 

 ment of Insects, perhaps, the best place in the United 

 States for the permanent deposit of types by working 

 specialists in entomology, and for the ultimate resting- 

 place of large collections made by individuals. 



The policy of the Museum at large, with regard to the 

 use of its collections by students, is a broad and liberal 

 one. Students are welcome in all departments, and every 

 facility is given to systematists of recognised standing. 



NOTES. 



It is proposed by the Administrative Council of the Pasteur 

 Institute to make an international appeal for subscriptions to 

 erect a monument to the memory of Pasteur. 



An ordinary meeting of the Royal Society, for the reading of 

 papers though not announced upon the printed list of arranged 

 meetings, will be held on the 28th inst. 



Sir Archibald Geikie and Prof. Story Maskelyne have 

 been elected corresponding members of the Munich Academy of 

 Sciences, in the Mathematical and Physical Section ; and Dr. 

 H. B. Svvete, of Cambridge, has been elected a corresponding 

 member in the Philosophical and Philological Section of the 

 same Academy. 



In accordance with the arrangement mentioned in our last 

 week's issue, Dr. A. G. Butler becomes Senior Assistant- 

 Keeper of the Zoological Department of the British Museum, 

 with special charge of the section of insects, and Mr. Edgar A. 

 Smith and Dr. R. Bowdler Sharpe have been promoted to fill 

 the two other assistant-keeperships. Mr. Vernon Herbert 

 Blackman, of St. John's College, Cambridge, has been ap- 

 pointed, after competitive examination, an assistant in the 

 Department of Botany, in the place rendered vacant by the 

 promotions consequent upon the retirement of Mr. Carruthers. 



