November, igo6.] 



KNOWLEDGE & SCIENTIFIC NEWS. 



3O0 



The "Unilens." 



The short account in the last number of " Knowledge " 

 of the " Unilens " has elicited a good deal of comment. 

 This correspondence is in accord with my preliminary 

 experiences. When first this simple idea occurred to me 

 I went to consult several opticians. But all said at once 

 that the use of one lens as a telescope was impossible. 

 I took a specimen into a certain shop and explained that the 

 arranirement acted most satisfactorily, at all events as 

 rejjarded my own eyesight. But the proprietor was 

 obdurate, and merely said "That will never do." " But 

 look (or yourself," I urged, holding the instrument before 

 him. Yet he would not even condescend to look through 

 it, saying, " You must have a second lens near the eye 

 before it can be any good," and I came away leaving him 

 absolutely unconvinced. Now some letters have been sent 

 to " Knowledge," of which two are by recognised 

 authorities on optics. One correspondent, dating from the 

 Athenseum Club, says: "A person with normal vision 

 . . . . cannot, with the ' Unilens ' focus anything that 

 is more than two or three feet beyond the glass. In order 

 to obtain a sharp image of an object beyond that distance, 



he must render himself artificially hypermetropic, by using 

 as an eyeglass a concave lens . . . . " and adds ; " If 

 the inventor finds the instrument as practically useful as 

 your note suggests that he does without an eyeglass, the 

 inference is that he has at least two dioptres of hj'per- 

 metropia, of which possibly he is unaware." An oculist 

 writes : " You say that it is always in focus ; now, I submit 

 that the rays of light, being convergent, are never in focus 

 for an emmetropic person. The very definition of an 

 emmetrope indicates this — one in whose eyes, without ac- 

 commodation, parallel rays are focusscd on the retina." 



Well, what is my answer? I find that nearly everyone 

 to whom I have shown the instrument (I can only recall five 

 exceptions) can see clearly through it, and find it useful 

 for magnifying distant objects. Are we, then, to under- 

 stand that all these people have " at least two dioptres of 

 hypermctropia? " If so, despite its long name, I think it is 

 a very convenient malady to suffer from. 



Mr. Wentworth Sturgeon, on the other hand, writes to 

 say that his father many years ago introduced a closely 

 similar instrument. It is but natural that so simple a device 

 should have often been tried before, and though I had 

 never heard of its being previously adopted, I do not claim 

 any originality' in the appliance beyond the details of its 

 present form. 



B. BADEN-POWELL. 



Ancient Mazer in Epworth Church. 



An early example of the Mazer is religiously preserved 

 among the old communion plate in the parish church 

 of Epworth. It was originally a wassail-bow! and was 

 presented to the church by Duke Thomas, one of the 

 great family of Mowbrays, who resided in the castle 



silver-parcel gilt. The rim of silver is ten inches in 

 diameter. The religious device engraved on a large 

 silver button in its centre has the Holy Family sur- 

 rounded by a moulding ornamented with rays of glory 

 and the figures of St. John the Baptist and St. Andrew 

 with St. Andrew's cross. 



A special interest will ' always attach to the old 

 communion plate of this church as having been so many 



Photo, by Newhitt it^ Son, Epicorth. 



Ancient Mazer in Bpworth Churcb. 



hard by, when he came to Lpworth to bid farewell to 

 his wife before his banishment by order of Richard II. 

 The vessel is now used as an alms dish; it is a curious 

 bit of antiquity, and the most interesting object in the 

 cluMili, It is constructed of maple wood, mounted in 



years in the possession of the Wesley family and as 

 having been used in the Holy Service by John and 

 Charles Wesley. 



The chalice is dated 1706; it is very beautiful and of 

 historic interest. The flagon is an ancient pewter. 



