Wortham unit
The Wortham unit was a unit of  created by a force field or tractor beam.

In 2267, when the  first monitored the power source of Vaal, the source was generating alternating cycles totaling one hundred to the twentieth  Wortham units. This was the total amount of energy Vaal was expending against the Federation starship. ()

Appendices

Background 
Based on de Forest Research's review of the episode's script, "We find no current scientific use of “Wortham.”"

According to the original draft of the script, Scott's original lines were:

"In terms of power, captain, the field is generated by pulsating impulses of energy totaling 100 to the 20th power Wortham units." 

In response, de Forest Research stated that "This line does not make sense." They then suggested the following "for scientific credibility": 

"In terms of power, captain, the field is maintained by pulsations of energy totaling 100 to the 20th power Wortham units."

The final aired dialogue stated:

"When we first monitored, it was generating alternating cycles totaling 100 to the 20th power Wortham units."

External link 
 

de:Wortham-Einheit
Measurements