66 G. H. KNIBBS. 



mean distance of travel from all points to the centres, which are 

 denoted by the letter C. The following table gives the results 

 absolutely, and also in percentages. 



I. — Mean distances of Travel and Total Length of Street. 



Fig 



(1) 



C2) 



(3) 



(4) 



(5) 



Mean Distance 



•443 



•446 



•378 



•348 



•381 1 



Total Length 



5-317 



5-142 



7-824 



7-142 



6-142 2 



Mean Distance % 



100, say, 



100-7 



85-4 



78-6 



86-0 



Total Length % 



100, say, 



96-7 



147-1 



134-3 



115-5 



On looking through this Table (I.) it is evident, first that (2) is 

 better than (1), for while the mean distance of travel is increased 

 only seven-tenths per cent., the total length of street is reduced 

 about 3J per cent. Hence for similar areas the ring form has an 

 advantage over the rectangular, in respect of reducing the total 

 length of street to be provided in a given area, and consequently 

 any approximation to the ring form will exhibit the same feature. 



In order to shew more clearly the relationship between mean 

 distance and total length of street to be provided, Table (II.) is 

 computed, shewing absolutely, and also in the form of a percentage 

 as compared with the rectangular system, the ratio of the total 

 length of street to the mean distance of travel to reach the centre C. 



II. — Ratio of Total Length of Street to Mean Distance of Travel 

 Fig. (1) (2) (3) (4) (5) 



Absolute 12-00 11-52 20-69 20-51 16-12 



Percentage 100-0 96-0 172:4 1709 1344 



A review of the figures in Table (II.) shews distinctly the 

 advantage of (2) over (1); an angle of 90° is however too great 

 between the radiating lines, so that any real consideration may be 

 confined to (3), (4) and (5), that is to what may be called the 

 'diagonal' system, the octagonal-radial system, and the hexagonal- 

 radial system. Comparing (4) with (3) it will be noticed first 

 that there is a slight advantage for (4) in respect to the street 



1 The quantities are £^tt, I + -^ir, (i + T V^ 2 ) ^ir» i + -h^> i + tVtt 



2 Similarly 3V r , 2 + tt, (3 + ^2)vV, 4 + v, 3 + tt- 



