In an early, simple hay tedder described in 1852 and manufactured in Edinburgh by the company of Mr. Slight, the two wheels, via a spur wheel and a pinion, drive a set of light wheels, the rake wheels; on these two rake wheels are mounted eight rakes, which pick up and disperse the hay.
It should be noted, how-ever, that only about 1 out of every 10 STEM workers has a high school diploma or less. Those with gradu-ate degrees in a STEM job earned more than $40 per hour, nearly $4.50 more per hour on average than those with non-STEM jobs.
STEM jobs offer a substantial salary premium. The average advertised salary for entry-level STEM jobs requiring a BA or higher is $66,123 compared to $52,299 for non-STEM jobs. This difference of around $14,000 represents a 26% premium. At the Sub-BA level, the average advertised entry-level salary is $47,856 for STEM jobs and $37,424 for non-STEM jobs. This difference of over $10,000 represents a 28% premium.