some Carbonates of the Calcite Group. 325 



Table I. 



Data for preparing ruler when distance from crystal to plate 



is 3 cm. 



Left side 



Eight side 



Left side 



Right side 



of ruler 



of ruler 



of ruler 



of ruler 



cm. 



cm. 



cm. 



cm. 



0.90 



34.06 



2.75 



12.85 



.95 



32.35 



2.80 



12.68 



1.00 



30.80 



2.85 



12.52 



1.05 



29.41 



2.90 



12.37 



1.10 



28.16 



2.95 



12.22 



1.15 



27.01 



3.00 



12.07 



1.20 



25.96 



3.10 



11.80 



1.25 



25.00 



3.20 



11.54 



1.30 



24.12 



3.30 



11.30 



1.35 



23.29 



3.40 



11.07 



1.40 



22.54 



3.50 



10.87 



1.45 



21.83 



3.60 



10.67 



1.50 



21.18 



3.70 



10.49 



1.55 



20.57 



3.80 



10.32 



1.60 



20.00 



3.90 



10.15 



1.65 



19.47 



4.00 



10.00 



1.70 



18.97 



4.10 



9.85 



1.75 



18.49 



4.20 



9.72 



1.80 



18.05 



4.30 



9.58 



1.85 



17.63 



4.40 



9.46 



1.90 



17.24 



4.50 



9.34 



1.95 



16.87 



4.60 



9.22 



2.00 



16.51 



4.70 



9.12 



2.05 



16.18 



4.80 



9.02 



2.10 



15.86 



4.90 



8.92 



2.15 



15.56 



5.00 



8.83 



2.20 



15.27 



5.10 



8.74 



2.25 



14.99 



5.20 



8.66 



2.30 



14.74 



5.30 



8.58 



2.35 



14.49 



5.40 



8.50 



2.40 



14.26 



5.50 



8.42 



2.45 



14.03 



5.60 



8.35 



2.50 



13.81 



5.70 



8.27 



2.55 



13.60 



5.80 



8.21 



2.60 



13.40 



5.90 



8.14 



2.65 



13.21 



6.00 



8.09 



2.70 



13.02 







