What is the nephroid of Freeth?

It is a curve described by the polar equation: r= 1+2sin(φ/2), (note the 2 in front of sine) named after and English mathematician T. J. Freeth (1819-1904) which first appeared in a paper he published in the London Mathematical Society in 1879.

It is considered an extention of Freeths strophoid which is generalized by the equation:

r= a[1+bsin(φ/2)]

See also information at: http://mathworld.wolfram.com/FreethsNephroid.HTML