336 



KNOWLEDGE. 



September, 1910. 



before the Quckett Club in 1888. and reproduced in 

 page 499 of The Journal of the Royal Microscoplcnl 

 Society for tiie same year. It is important to 

 remember this, because tlie new structure, visuallw 

 is entirel)- the resuh of aperture, and not 

 until some f(5ur years later, not indeed until 

 after acquiring a 2 mm. apo. of Zeiss, of 

 1'4() N..\. \\as the secondary structure seen and 

 photographed. The "pins'" were tirst discovered 

 by a cheap one-twelfth inch oil immersion b\- S\\-ift 

 and Son, of 1'25 N.A. : the interspaces blank. The 

 apochromatic filled the interspaces with structure, 

 proving the scale to be as worthy a test as e\'er. In 

 all cheap oil immersions now the X..\. has been 

 increased to I'.iO, and what with that and the new- 

 Jena glass used in their construction, the secondar\- 

 structure should be easily seen. T\\(j conditions. 

 howe\'er, are necessary to see the scale untler tlie 

 most favourable aspect. It must be in ojjtical 

 contact with the cover, and the lens adjusted to the 

 proper tube lengtli. With the scale sunk to the slip 

 there is an interxal of air between, causing the oil 

 immersion to work no tn-tter than a dr\" glass. For 

 comparison between the photo-micrograjihs and 

 enlargements, illustrating the present article and 

 small cone \\ork. the reader is referred to three 

 reproductions of photo-micrographs and an enlarge- 

 ment of the scale, facing page M)5 of Tlie Journal 

 of the Royal Microscopical Society for 1892. It is for 

 him then to make his own comments. 



When one proclaims a new doctrine one should 

 justil\" the faith within him. but if the writer is asked 

 to explain the nature of the secondary structure, he 

 can only sa_\' he does not know. Yet he is prepared 

 to pin his faith upon " pins," and for the reason that 

 one of the prints, in fact two, show positi\e e\-idence 

 no diffraction effects can explain away. It might be 

 possible, for instance, to deny the existence of a bone 

 in a human leg, but if that bone was broken and 

 protruding through the flesh, denial would be no 

 longer possible. To compare small thiiii^s w ith great, 

 this is just what has hai>pened to one of the scales. 

 Ruptured by bending on itself, two of the "pins" 



are left sticking out by themselves from the general 

 line (see Figure 4). Another print exhibits isolated 

 " pins," photographed from a shewn slide of scales 

 (see Figure 5). Unfortunatel)- both slide and nega- 

 tive ha\'e vanished into the Imdio of lost things, 

 and, consequentl}-, an eidargement cannot be pro- 

 duced. Of course, an enlargement can show no more 

 detail than the original negative : on the other hand 

 it can make tliat detail much more apparent and 

 striking. 



It is onl\' pa\'ing a proper tribute to one pre- 

 eminent in both branches of photograph}', to sa}' that 

 Mr. Alfred Pringle was the first to photograph the 

 " pins," onh' he called them " French nails." 

 Unfortunately the print he sent the writer is also 

 gone to the limbo of lost things, neither can Mi'. 

 Pringle find the negative, nor a jirint. though 

 remembering the conversation passing between us 

 perfectl}'. Coming fresh to the microscope, ha\'ing 

 no conventions to hamper him, he simplv photo- 

 graphed what he saw under an oil immersion of 

 r25 N.A.. onl\' to find the result ridiculed. His 

 photograph did not, however, show secontlar\' 

 structure, and in this respect the w riter believes his 

 own to he unique. 



Mr. Nelson's remarks on his own interpretation of 

 the scale are as follows: "An examination of a 

 Podura scale in a critical manner with niodern 

 apochroniatic objectives, ilhmiinated b}' a full axial 

 cone from an achromatic oil inimersion condenser, 

 shows the exclaniation niarks ha\e V-shaped heads, 

 causing them to assume the appearance of the 

 cuneiform marks on the Assyrian iiiscriptions. l>oth 

 the pin ami knobbed heads of the exclamation marks 

 are due to some obliquity in the illumination, 

 especialh' in a direction froni root to ti[i. When the 

 full axial cone is perfectly central the knobbed and 

 pin-shaped heads disappear." 



In answer, the writer can only say that the 

 supposition that Mr. Pringle and himself were 

 eniploxing oblique light all the tinie they thought 

 the^■ were using central, is one he cannot for him- 

 self accept on a simple ipse dixit. 



THE BRITISH SCHOOL OF ARCHAEOLOGY IN EGYPT. 



The exploration work of Professor Minders Petrie 

 and his students was carried on during the past vear 

 at Memphis and Medum. At the latter place a 

 number of S'-idiitured tombs were found, and one 

 mastaba had two chambers covered- with incised 

 sculpture which was inlaid with coloured paste. 

 This method of decoration has never been met w ith 

 elsewhere, and is looked upon as one of the earl\' 

 experiments which was never repeated. The age of 

 the tombs is that of Sneferu, the last King of the 

 third dynasty (4650 B.C.) The tombs were all re- 

 moved: one of the special chambers remains at Cairo, 

 while the British School of Archaeologx' was allowed 

 to retain the other, and parts of the sculpture were 

 shown at the annual exhibition of the antiquities 



brought honie, at University College during July 

 last. The task of the School included the removal of 

 a hundred feet of sculptured wall, ten feet high, as 

 well as of the massive roof. At Memphis the palace 

 and temple of Ptah and the pottery kilns were 

 examined. The temple is the most important, his- 

 toricallv. in all Egypt, and Professor Petrie is to be 

 congratulated upon overcoming the scruples of the 

 owners, who at first were reluctant to allow excava- 

 tions to be made, and in securing contracts in 

 connection with a good deal of the ground. Blocks 

 bearing portraits of Amenhotep III. and Amasis were 

 respectively' found in two sanctuaries of quartzite 

 sandstone which were brought to light in the course 

 of the excavations made in the axis of the temple. 



