allow singular alchemy sphere

glossary.tex

@@ -983,6 +983,7 @@ Set the darker die to `\dicef{6}' and roll the other.  If this roll fails, it fa
 
 \longnewglossaryentry{sphere}{
   name={Spheres},
+  text={Sphere},
   prefix={a\space},
   parent={witchcraft},
   type={mech},