SPIRAL NEBULAE — CURTIS. 
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from these counts estimate that there are at least 700,000 spiral 
nebulae accessible with large reflectors. 
3. The most anomalous and inexplicable feature of the spiral 
nebulae is found in their peculiar distribution. They show an ap- 
parent abhorrence for our galaxy of stars, being found in greatest 
numbers around the poles of our galaxy. In my counts I found an 
approximate density of distribution as follows: 
Galactic latitude rf 45° to + 90° 34 per square degree. 
Galactic latitude — 45° to — 90° 2S per square degree. 
Galactic latitude + 30° to + 45° and —30° to — 45° 24 per square degree. 
Galactic latitude — 30° to -}- 30° 7 per square degree. 
No spiral has as yet been found actually within the structure of the 
Milky Way. We have doubled and trebled our exposures in regions 
near the galactic plane in the hope of finding fainter spirals in such 
areas, but thus far without results. The outstanding feature of the 
space distribution of the spirals is, then, that they are found in great- 
est profusion where the stars are fewest, and do not occur where the 
stars are most numerous. This distribution may be illustrated 
graphically as follows : 
THE FACTOR OF SPACE DISTRIBUTION. 
400,000 ±: Spiral nebulae 
Our own stellar universe 
is shaped like a thin lens, and is perhaps 
3,000 by 30,000 light-years in extent. In this 
space occur nearly all the stars, nearly all the new stars, nearly 
all the variable stars, most of the diffuse and 
planetary nebulae, etc., but 7io spiral 
nebulae. 
300,000 ± Spiral nebulae. 
