August i, 1895] 



NA TURE 



321 



or ingenious execution. But at the same time, and on 

 the other hand, there is no small danger that we may fail 

 to give proper recognition to those other astronomers 

 whose lives, unmarked by brilliant achievements, have 

 been devoted to labours which are none the less valuable 

 because they have been accomplished while quietly 

 pursuing recognised lines, and are therefore devoid of 

 conspicuous originality. In particular, the work of com- 

 putation and arithmetical reduction of observations, 

 without which the observations themselves either cannot 

 be made or must remain almost entirely useless, is apt to 

 fall into disrepute, as being wholly mechanical and un- 

 enterprising. This is certainly to be regretted ; for just 

 as a victorious general marching forward in the enemy's 

 country' must depend for his ver>' safety on the fidelity 

 and capacity of those officers who hold the conquered 

 territory, so our scientific knowledge is liable to become 

 disconnected and fragmentary' unless we have capable 

 men ready to perform the task of computing from the 

 observations, and co-ordinating the results achieved in 

 more exciting spheres of scientific work. If the pursuit 

 of such unostentatious work lead to the efiacement of the 

 worker, our gratitude should be even all the greater for 

 the self-denial exhibited and practised. Of S"ch a man 

 we have recently had to lament the loss, owing to the sad 

 death of Dr. Tietjen, of Berlin. 



Friedrich Tietjen was bom in Oldenburg, in the year 

 1834 ; we therefore lose his ser\ices at the comparatively 

 early age of sixty-one. He studied mathematics and 

 astronomy at Gottingen, and subsequently at Berlin, with 

 which latter city he has been continuously connected. In 

 1861, he became attached to the staff" of the Berlin 

 Observatory, and in one or other capacity this connection 

 remained unbroken till the time of his death. He was 

 appointed Professor of Astronomy in the University of 

 Berlin, and Director of the Rechcninstitict, allied to the 

 Berlin Observatory. In his earlier career, Dr. Tietjen 

 occupied himself with the observations of comets and 

 asteroids, discovering in this way the asteroid Semele. 

 To his activity and devotion the pages of the Astrono- 

 inischc Nachrichten abundantly testify. He is also known 

 as the calculator of several cometary orbits, and also of 

 the orbits and ephemerides of many asteroids. Some 

 twelve years later. Dr. Tietjen became superintendent of 

 the Rerliner Astrowmischcs Jahrbiich,2i'nA his reputation 

 in that capacity is not less assured than that of Dr. 

 Powalky, who had preceded him in that office. As 

 official director he paid great attention to shortening the 

 labour of the necessary calculations as far as possible. 

 Some of his methods have been published, others are not 

 so well known, ill-health having prevented him from giving 

 them to the world. Of the value and of the accuracy of 

 this publication under the superintendence of Dr. Tietjen 

 it is unnecessary to speak here, for it is sufficiently well 

 know-n. Probably his most useful work was that done in 

 superintending the preparation of the ephemerides of 

 the small planets, the continual and rapid increase in the 

 number of which, while it enormously increased his work, 

 had likewise the effect of lessening the interest in this 

 class of discoveries. While the national almanacks of 

 other countries practically discontinued the publication 

 of this class of ephemerides, Dr. Tietjen loyally struggled 

 to supply sufficient information to ensure the observation 

 of the small planets. Those who have attempted the 

 determination of the mass of Jupiter from the perturba- 

 tions of these bodies, and similar kinds of work, know- 

 how to appreciate the labours of Dr. Tietjen, by which 

 the continuous observation from opposition to opposition 

 has been rendered possible. 



This skilled mathematician and remarkably facile com- 

 puter died at Berlin, on June 21, deeply lamented by his 

 numerous friends, and regretted by many who have 

 profited by the devotion of his quiet unambitious life to 

 the service of astronomy. 



NO. 1344, VOL. 52] 



THE MAXIM FLYING MACHINE. 



ON Friday, July 5, a large party of scientific men paid 

 a visit, by invitation of Mr. Hiram .Maxim and Mr. 

 Brodrick Cloete, to Baldwyns Park, Bexley, to witness a 

 trial of the celebrated flying machine, and the latest 

 development in the direction of mechanical flight. 



The invitations were carefully distributed among those 

 who were competent to judge of the magnitude of the 

 task to be attempted, and who were prepared to examine 

 closely the ingenious mechanical details by which it was 

 clearly demonstrated that the machine had ample power 

 to lift itself off" the ground, carrying with it a supply of 

 fuel and water, and a crew for the navigation. 



An unscientific crowd of spectators might have become 

 unmanageable, and might have developed iconoclastic 

 tendencies (like the Weser boatmen with Denis Papin's 

 original steam vessel) when the machine did not take to 

 flight immediately and disappear from their astonished 

 gaze. 



"As lewed people demelh comunly 



Of thinges that ben maad more subtilly 

 Than they can in her lewednes comprehende 

 They demen gladly to the badder ende " 



But the Bexley machine is purposely designed of 

 extreme size, with the intention of thoroughly testing and 

 elaborating' the details of the mechanism, and of measur- 

 ing the lifting power, within immediate reach of a work- 

 shop and skilled mechanics, more than of actually 

 taking to the air ; this will probably be first attempted 

 with a much smaller machine, capable of lifting one man. 

 of jockey-like proportions, and mounted on a boat on a 

 lake, so that short flights, like those of a flying fish, can 

 be attempted for initial practice. 



The lifting force of the machine is measured automatic- 

 ally as it runs along a railway track about half a mile in 

 length, as shown in the accompanying illustration (Fig. i), 

 and the machine is prevented from taking to flight by 

 wheels running underneath the outer wooden rails, seen in 

 the figure ; for much yet remains to be done in the way of 

 practice in vertical steering before taking leave of the 

 earth ; the chief difficulties of the Aviator beginning 

 when he wishes to descend and alight on the ground 

 again. 



Chaucer did not realise the difficulties of the problem 

 when describing so jauntily the Bronze Horse in the 

 Squieres Tale : — 



■ ' This same stede shall bare yo w ever-more 

 With-outen harm, til ye be ther yow leste. 

 Though that ye slepen on his bak or reste ; 

 .\nd turne ayejTi, with wrything of a pin."' 



" But whan yow list to ryden any- where, 



Ve moten trille a pin, stant in his ere — " 

 " Bid him descend, and trille another pin," 

 " Trille this pin, and he wol vanishe anon.' 



The " wrything of a pin " is not inapt in describing the 

 dominating gyrostatic brain of the .Aviator, designed by 

 Mr. Maxiin to perform the vertical steering automatically. 



The Bexley machine, complete with the water, naphtha 

 fuel, and crew of three men on board, weighs Sooo lb. ; 

 and running at forty miles an hour with a pressure of 

 275 lb. per square inch, the engines develop 360- 

 horse power, the thrust of the screws is :ooo lb., and 

 the lifting effect of the aeroplanes and wings, 40CO 

 square feet in area, is 10,000 lb. 



A thrust of 2000 pounds at 45 miles an hour gives 

 240 thrust horse-power ; or, with a speed of advance 

 of the screw of 60 miles an hour, 320 indicated horse- 

 power. 



The total projected disc area of the screws is 500 square 

 feet, each screw being nearly iS feet in diameter, -with a 

 pitch of 16 feet ; and thus recpiiring 330 revolutions a 

 minute to give a speed of advance of 60 miles an hour. 



