April-], 1881] 



NA TURE 



527 



impossible to reconcile a period so exalted with the ceiling 

 of the so-called Memnonium and the date of the heliacal 

 rising of the dog- star on the calendar of Thothmes III. 

 at Elephantine. Every fact connected with the Exodus is 

 a subject of continual dispute, dates, line of march, names 

 of the Pharaoh?, place of the House of Bondage whence 

 the Jews swarmed out. The only safe view to take is 

 that the problem is insoluble, and that its resolution 

 should be tied up with the sheaf of paradoxes collected 

 by De Morgan. Mr. Villiers Stuart found the cultivation 

 of sugar prosperous, by means, though, of that apology for 

 slavery "forced labour," and he is indignant at the 

 sufferings of the unhappy fellaheen, as also at the urgent 

 scheme of taxation and the system of baksheesh and 

 official briber)' which pervades the modern as extensively 

 as it did the ancient land of bondage ; but corv^es, it 

 appears, are necessary for the payment of Daira bonds, 

 and " the drachm," as in the Roman times, must be wrung 

 out of the hard hands of peasants. While however glancing 

 at the modern state of Egypt the interest of the writer is 

 concentrated on the Egypt of the past, Pharaohs, their 

 queens and their princesses, and a fair popular account is 

 given of Thebes. His weakness is a love of dabbling in 

 etymology, and venturing out of his depth on general ques- 

 tions of comparative philology. Although, for example, an 

 occasional word may resemble its Greek or Latin equiva- 

 lent, the construction of the hieroglyphic or old Egyptian 

 and the Coptic is totally different from those two classical 

 tongues, the Egyptian having a closer resemblance to the 

 Semitic than the Aryan or Indo-Germanic languages. 

 As to the Etruscan, the few known facts about its con- 

 struction point to the Turanian or Tartaric family rather 

 than the Egyptian. The origin of the Egyptians is still 

 involved in obscurity, and belongs to the province of 

 conjectural ethnology. More Caucasian in the north 

 and at the earliest period, more Nigritic on the south and 

 at a later epoch, the Egyptians seem historically a mixed 

 race, a fusion of conterminous races of Northern Africa, 

 and Eastern foreigners, and Nigritic blood. The oldest 

 inhabitants still remain a mystery. One theory is that the 

 Egyptian was the primitive man of a vast continent, the 

 last representative being the aboriginal Australian. 

 Amongst other interesting points are visits to the Der- 

 vishes, espetially the fortune-tellers, and a description of 

 the ride of the Sheikh of the Saidieh over the bodies of 

 living men, who must have suggested to the apostle, had 

 he seen him, the subject of Death on the Pale Horse. 

 Like the car of Juggernaut, the Sheikh of the Saidieh is 

 said to have been abolished. The ceremony might have 

 been the relic of an old Egyptian one, and Pharaoh riding 

 over his prostrate enemies may have anticipated the 

 Sheik of the Saidieh. Altogether the work is entertaining 

 and amusing : it is not so dry as a guide or handbook, 

 nor so learned as an Egyptological history such as that of 

 Brugsch-Bey, nor so elaborate as Wilkinson's Manners 

 and Customs, and Topography, or other travels by pro- 

 fessed Egyptologists ; but its style is light and sparkling, 

 and the principal details of history, mythology, and archaeo- 

 logy have been fairly mastered. In the minute details of 

 philology it is weak, but they do not affect the general 

 reader, and are easily set right tn passant by the expert. 

 They will do no harm to scientific research, and they will 

 amuse and to some extent instruct the public. The plates 



are also fairly done, and their colouring renders them more 

 than usually attractive. It is decidedly agreeable to while 

 away the monotony of a voyage down the river of the 

 desert, as the Nile may be justly styled, and to those 

 whose only travels are round their room, it will convey 

 some pleasing impressions of what a visit to Egypt might 

 show them. 



LETTERS TO THE EDITOR 

 \_T7te Editor does not hold himself responsible for opinions expressed 

 by his correspondents. Neither can he undertake to return, or 

 to correspond with the writers of, rejected itianuscripts. No 

 notice is taken of anonymous communications. 

 [ The Editor urgently requests correspondents to keep their letters as 

 short as possible. The pressure on his space is so great thai ii 

 is i?npossible otherwise to ensure the apl>earance even of com- 

 munications containing interesting a7td novel facts. \ 



Improved Arrangement of Scale for Reflecting 

 Instruments 



The inconvenience resulting from the position of the scale in 

 the ordinary well-known form of Thomson's reflecting galvano- 

 meter must have been experienced by all who have had occasion 

 to use it much, and especially by uiyoptic individuals. This I 

 have been able to eliminate very easily, as hereafter described, 

 so that there is no further craning over to see ** the spot," or 

 getting in ones *' light " in so domg. 



The scale is mounted as shown in the sketch, \\hich gives a 

 front view of one end of the scale and a cross-section of the 

 same. 



B is a wooden scale-board with longitudinal slot, as shown at 

 c ; P is the paper scale, cut so that nil the division lines reach 

 the inferior edge ; A is a slip of plane glass, finely sjround as to 

 its lower half on the side towards c, from one end of the slip 

 to the other ; the scale is so placed that the lo'Acr end of the 

 division lines just touches the ground part of the glass slip. The 

 image of the slit with a fine wire stretched across it is focussed 

 in the ordinary manner on the ground part of the glass, and will 

 of course be clearly seen by the observer on the opposite side of 

 the scale; as the line and printed divisions are in the same 

 plane, there is no parallax ; and a great increase in accuracy of 



\ 3^ 3S 3e 37 M 30 



CZD 



reading the position of the hair line is obtained, owing to the 

 gi-eater ease of observing that two lines coincide when end on to 

 one another than when superimposed ; and further, from the 

 circumstance that the room need not be darkened. 



This arrangement has been introduced at the beginning of this 

 year by me in the testing-roora of Messrs. Siemens Brothers and 

 Co. at Woolwich, and has been most readily accepted by all 

 my assistants, and I venture to say that any w ho adopt this 

 arrangement will never return to the previous form. 



1 may state that I place the lamp and its slit on one side and 

 reflect the beam of light on to the galvanometer by a mirror or 

 total reflection prism, and further by means of two long plane 

 mirrors reduce the actual distance betw een the galvanometer and 

 scale, so as to have everything close to the observer's hand. The 

 scale I have adopted is divided into half millimetres, and it is 

 perfectly easy to read to a quarter of a division, and with a 

 hand magnifying-glass still further. 



This method is of course .applicable to any physical instru- 

 ments which are read by a reflected spot, and as there are no 

 " patent rights " it is placed at the disposal of all. 



Charlton F. Jacob 



A Note on Flame-Length 



Three years ago, whilst endeavouring to make use of flame- 

 length as a means of testing the economic values of different 

 qualities of coal-gas by the determination of their specific flame- 



