anchor.diff:    <colgroup>
       <col />
       <col />
  +    <col />
  +    <col />
     </colgroup>
     <thead>
       <tr>
  -        <th>Direct</th>
  -        <th>Diffuse</th>
  -        <th>Postcode</th>
  -        <th></th>
  +      <th>Postcode</th>
  +      <th></th>
         <th></th>
         <th></th>
       </tr>
  
positive.code:   <tbody>
    <% @irradiances.each do |irradiance| %>
      <tr>
          <td><%= irradiance.direct %></td>
          <td><%= irradiance.diffuse %></td>
          <td><%= irradiance.postcode_id %></td>
          <td><%= link_to 'Show', irradiance %></td>
        <td><%= link_to 'Edit', edit_irradiance_path(irradiance) %></td>
        <td><%= link_to 'Delete', irradiance, confirm: "Are you sure?", method: :delete %></td>
      </tr>
  
negative.code: 
  <br />
  
  <%= link_to 'Add irradiance', new_irradiance_path %>
  