July 12, 1877] 



NATURE 



213 



for concluding that he had placed too great reliance upon 

 the value of the mean motion determined in his memoir, 

 and while obtaining a new value (about 650") which 

 would assign for the period of revolution in 1844 abovt 

 i994'o days, he intimates the necessity of searching for 

 the comet in future on the supposition that this period 

 may be in error ± 30 days. At this distance of time or 

 at the end of the sixth revolution since 1844, so great an 

 amount of uncertainty of course renders the preparation 

 of limited ephemerides useless, but it may be observed 

 that the period finally deduced by Prof Briinnow would 

 bring the comet to perihelion again in the present 

 summer, and it will certainly be worth while to keep a 

 close watch upon those regions of the heavens which its 

 path must traverse on this hypothesis ; we might indeed 

 expect, if the comet continues in the same condition as 

 in 1844, that it would not escape detection, should the 

 perihelion passage fall between the beginning of the 

 present month and the middle or end of October. On 

 July 14 its orbit is thus projected on the sky, the positions 

 consequently indicating the line in which it should then 

 be found according to the different suppositions as to 

 the date of perihelion passage : — 



.'^'g'^' Declination. Distance from Intensity 



Ascension. Earth. of 1 ighi. 



+ 40 days 



- 40 



- SO 



- 60 



603 



43 'o 



21'2 

 350 I 



321 -6 



289-3 



+ 19-3 

 + 13-4 

 + 30 



- 136 



- 24-8 



- 30-1 



1-89 



112 

 0-64 

 0-39 

 0-34 

 0-38 



0-I7 

 o'56 

 I -68 

 4 02 

 478 

 3 -60 



While it is of importance that an eftbrt should be made 

 to recover the comet, now to all intents lost,\n the prrsent 

 year, no surprise need be occasioned if the endeavour 

 should prove fruitless. It is quite possible that the mean 

 motion in 1844 was of such amount as would bring the 

 comet, with the influence of planetary perturbation into 

 so close a proximity to Mars at the end of August, 1866, 

 as to occasion very material changes in the elements of 

 its orbit ; and again there is the possibility that, as Dr. 

 von Asten suspects has been the case with Encke's comet, 

 it may have encountered one of the minor planets, and 

 with the result of a sensible change in its motion. 



And it is to be borne in mind to whatever cause or 

 causes the circumstance may be due, that De Vico's 

 comet has been shown by M. Le Verrier and Prof. 

 Briinnow to be with great probability identical with the 

 comet of 167S observed by Lahire at Paris ; yet in the 

 long interval from 167S to 1844 there is no record of a 

 comet which can be identified with it, and in the early 

 part of its appearance in the latter year it was visible to 

 the unassisted eye. It does appear strange that in the 

 days of Messier and Pons the comet should have escaped 

 detection at one or other of its returns. 



While writing on De Vico's comet we may mention 

 that in heliocentric longitude 33g"'6 this body approaches 

 very near to the orbit ot the periodical comet of D'Arrest, 

 of which obser\'ations may be expected in the present 

 year. The distance is within 0-0055 of the earth's mean 

 distance from the sun, or about 507,000 miles, rather more 

 than twice the moon's distance from the earth, but it does 

 not appear likely that there has been any actual close 

 approach of the two comets during the last fifty or sixty 

 years. 



The Late Professor Heis.— We regret to record 

 I ' the sudden death of Prof Edward Heis, the well-known 

 i German astronomer, which occurred on June 30 from an 

 ',; attack of apoplexy. Prof. Heis was born in 1806, com- 

 pleted his studies at Bonn in 1827, and received in 1852 

 a call to the ordinary professorship of mathematics and 

 j astronomy at the Royal Academy of Miinster, Westphalia, 

 . which he filled until the time of his death. He was a 

 I most diligent and accurate observer in the particular 



branches of astronomical research to which he devoted 

 himself. His "Atlas Ccelestis Nova" may be considered 

 the standard work for magnitudes of the stars visible in 

 central Europe, his acute vision enabling him to add a 

 large number of stars of what he calls 67m. not included 

 in ArgelandePs " Uranometria." While resident at Aix- 

 la-Chapelle previous to his appointment to Miinster he pub- 

 lished the results of ten-years' observatiofs upon shooting- 

 stars which were carefully discussed. In 1875 appeared 

 his observations on the zidiacal light, extending over the 

 twenty-nine years, 1847-1875, and forming No. I. of 

 PuHicatioin of the Royal Observatory at Minister : it is 

 a most important addition to our collection of observations 

 of this as yet little understood phenomenon. From 1858 

 to 1875 he edited the IVocheiisehri/t fiir Astronomie, a. 

 periodical better known on the Continent than in this 

 country. Prof Heis was also the author of a collection 

 of examples and problems in general arithmetic and 

 algebra, which, we believe, has reached the forty-fifth 

 edition in Germany. His observations of variable stars 

 were conducted upon a system of extreme care, his 

 researches in this direction being encouraged and guided 

 by Argelander ; he first established the variability of that 

 irregular star t Aurigas, not without a long course of 

 assiduous observation. He was an excellent draughtsman, 

 and produced many fine pictures of nebulie, though, unfor- 

 tunately, supplied with very limited optical means. 



THE CAXTON EXHIBITION 

 r T is no' too much to say that Science has been 

 '^ advanced by the art of printing more than by any other 

 of the world's inventions, for by it not only has the 

 knowledge of scientific truth been spread throughout the 

 world, but it has been perpetuated to all time, and the 

 names of great heroes in science have been rendered 

 immortal. Long after sculptured monaments, commemo- 

 rative of the lives and work of great men have crumbled 

 away, their written works remain, and the art of printing 

 has contributed more than anything else to the bringing 

 about of that result. The names of some of the greatest 

 philosophers the world has ever seen wojld have had but a 

 narrow and comparatively ephemeral celebrity, were it 

 not for the record of their lives and writings which the 

 productions of the printing press have preserved to them. 



But great as have been the advantages which Science 

 has derived from the printer's art, she has, in return, 

 conferred as many and as important benefits upon the 

 development of that art ; and this is recorded in unmis- 

 takable language in the Caxton Collection, whiuh, though 

 (probably for want of space) very deficient as far as 

 modern printing machines are concerned, constitutes a 

 most interesting and instructive series of historical and 

 typical forms, in which the rise and development of 

 printing machinery may be traced from the early screw 

 presses of wood used by Caxton and the early printers, 

 through the Stanhope and lever presses of the last 

 century, to the powerful steam machinery of the present 

 day. 



The principal aim of the designers of printing machinery 

 has always been to obtain increased rapidity of working ; 

 and during the last fifty years this has been brought to 

 an extraordinary degree of perfection. It was considered 

 a wonderful feat when, in the year 1814, the celebrated 

 Konig machine was started, throwing off 1,100 sheets of 

 the Times newspaper per hour ; but this number was 

 doubled by Konig's second machine, which he brought 

 out ten years after. In the year 1827, by mean"; of 

 Applegarth and Cowper's four-cylinder machine, the yield 

 was raised to 5,00c per hour, and in 1848 the celebrated 

 "Times" vertical machine was erected, which produced 

 1 2,000 single impressions per hour. The next advance was 

 made by Richard Hoe, who, in 1857, introduced his 

 cylinder machine into this country, where it was first 



