BAIRD &TATLOCK (LONDON) LTD. 



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Beck-Thorp Diffraction Spectroscopes. 



This series of high-class spectroscopes may be said to be the first serious attempt to apply the advantages of 

 Diffraction Grating to the whole field of spectroscopic research. The list includes small instruments to be 

 carried in the pocket by those who are connected with colour printing, or any chemical or colour industry, while 

 the price of the simplest form is so small that every physiology student, every chemical student, every engineer 

 should have one. 



From this form the list proceeds to the more perfect instrument with accurate scales of measurement, following 

 on with a Chemical Spectroscope of great dispersion, a Sun Prominence Spectroscope, and finally a Wave Length 

 Spectroscope of such accuracy that the wave length of light may be determined with accuracy. 



5763 



5763 T Beck-Thorp " Minimum " Pocket Diffraction Spectroscope ... 



This instrument gives a dispersion of about 20, or about double that of the ordinary direct vision prismatic 

 instrument. It will readily show the more prominent Frauenhofer lines and will distinctly show the rainband lines. 

 It has been supplied largely to the Universities in England for the use of students, and is suitable as a pocket 

 instrument for all classes of colour work and chemical industries. 



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5764 



5764 T Beck -Thorp " Regular " Pocket Diffraction Spectroscope 



This instrument has a dispersion of about 30, and shows hundreds of lines in the Solar Spectrum, the D 

 line being well separated. The B group is admirably shown. It has a finely made adjustable platinoid slit and a 

 sliding focussing adjustment. It is suitable for the same class of work as No. 5763. 



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5765 



5765 T Beck-Thorp Patent Reading Pocket Diffraction Spectroscope 



This instrument has the same optical qualities as No. 5764 last described, but has a most important addition. 

 Upon looking through the instrument the spectrum will be seen, and above the top will be seen an illuminated 

 arrow point. A graduated revolving milled head moves this point along the spectrum, and the position of any 

 line can thus be registered. The gradations of the revolving drum are observed through the lens by a slight shift 

 of the eye, and in this way the positions of numbers of lines can be rapidly recorded during even a short observation. 

 One of the minor advantages of this system of reading is that the pointer is illuminated by the actual source of light 

 that gives rise to the spectrum, and therefore, if the spectrum is brilliant, the pointer will be brilliant ; if the 

 spectrum is dim, the pointer will be dim, and the brightness of one will not overpower the other, but the great 

 advantage of this method of reading is that the readings correspond to the wave-lengths of light. The whole 

 spectrum is divided into 500 divisions, and a glance at the sun, reading two or three important and easily recognised 

 lines, at once gives the ratio that the scale bears to the actual wave length. 



This instrument has been supplied to physical laboratories. It is being used by the medical profession for 

 blood research, and is specially suitable for the processes of steel manufacture, which depend for their success oa 

 spectrum analysis. 



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