If a size of a detector is very small compared to the distance traveled by the light, any light that is scattered by a particle, either in the forward or backward direction, will not strike the detector. (Bouguer was studying astronomical phenomena, so this condition was met.) In such case, a plot of − − ln ⁡ ⁡ ( T ) as a function of wavelength will yield a superposition of the effects of absorption and scatter. Because the absorption portion is more distinct and tends to ride on a background of the scatter portion, it is often used to identify and quantify the absorbing species. Consequently, this is often referred to as absorption spectroscopy, and the plotted quantity is called "absorbance", symbolized as A . Some disciplines by convention use decadic (base 10) absorbance rather than Napierian (natural) absorbance, resulting in: A 10 = μ μ 10 d (with the subscript 10 usually not shown).